P[0] = 1;
for (int i = 1; i < N; i++)
{
	P[i]=P[i-1]*X[i-1];
}
Q[N-1] = 1;
for (int i = N-2; i >= 1; i--)
{
	Q[i]=Q[i+1]*X[i+1];
}

for (int i = 0; i < N; i++)
{
	M[i]=P[i]*Q[i];
}

//equate two arrays
private static boolean isEqual(char [][]arr1, char [][]arr2) {
		if(arr1.length!=arr2.length) return false;
		boolean res = true;
		for(int i=0; i<arr1.length; i++) {
			res = res & Arrays.equals(arr1[i], arr2[i]);
		}
		return res;
	}
	
//rotate clockwise 90 degrees
private static char [][]rotate90(char [][]arr) {
	char [][]ret = new char[arr.length][arr[0].length];
	for(int j=0; j<arr[0].length; j++) {
		for(int i=0; i<arr.length; i++) {
			ret[i][j] = arr[j][i];
		}
	}		
	//print(ret);
	return reflect(ret);
}
	
//reflect horizontally	
private static char [][]reflect(char [][]arr) {
	char [][]ret = new char[arr.length][arr[0].length];
	for(int i=0; i<arr.length; i++) {
		for(int j=0; j<arr[0].length; j++) {
			ret[i][j] = arr[i][arr[i].length-j-1];
		}
	}		
	//print(ret);
	return ret;
}

//prints for debugging	
private static void print(char [][]arr) {
	for(int i=0; i<arr.length; i++) {
		System.out.println(Arrays.toString(arr[i]));
	}
	System.out.println();
}

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.util.Stack;
/*
ID: kanishk1
LANG: JAVA
TASK: moat
*/

public class moat {
	static class Point implements Comparable {
		public int x; public int y;
		Point pv;
		public Point(int x, int y) {
			this.x = x;
			this.y = y;
		}
		public void setPivot(Point pv) {
			this.pv = pv;
		}
		public int compareTo(Object o) {
			Point p = (Point)o;
			double a1 = ((y-pv.y)*1.0)/(x-pv.x);
			if(a1<0) a1 = 2+a1;
			double a2 = ((p.y-pv.y)*1.0)/(p.x-pv.x);
			if(a2<0) a2 = 2+a2;
			if(a1>a2) return 1;
			else if(a1<a2) return -1;
			else return y-p.y;
		}
	}
	static Point []points;
	 public static void main (String [] args) throws IOException {
		    
		 // Use BufferedReader rather than RandomAccessFile; it's much faster
		    BufferedReader f = new BufferedReader(new FileReader("moat.in"));
		                                                  // input file name goes above
		    PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("moat.out")));

		    int N = Integer.parseInt(f.readLine());
		    points = new Point[N];
		    int lx = Integer.MAX_VALUE, ly = Integer.MAX_VALUE;
		    Point p = null;
		    for(int i=0; i<N; i++) {
		    	StringTokenizer st = new StringTokenizer(f.readLine());
		    	int x = Integer.parseInt(st.nextToken());
		    	int y = Integer.parseInt(st.nextToken());
		    	
		    	points[i] = new Point(x,y);
		    	if(y<ly) {
		    		ly =y;
		    		lx = x;
		    		p = points[i];
		    	}
		    	else if(y==ly && x<lx) {
		    		lx = x;
		    		p = points[i];
		    	}
		    }
		    for(int i=0; i<N; i++) {
		    	points[i].setPivot(p);
		    }
		    Arrays.sort(points);
		    for(int i=0; i<points.length; i++)
		    {
		    	System.out.println(points[i].x+" "+points[i].y);
		    }
		    Stack stack = new Stack();
		    stack.push(points[0]);
		    stack.push(points[1]);
		    for(int i=2; i<points.length; i++) {
		    	Point top = (Point)stack.pop();
		    	Point second = (Point)stack.pop();
		        int o = Cross_product(second, top, points[i]);
		        stack.push(second);
		        stack.push(top);
		        if(o == 0) {
		        	stack.pop();
		        	stack.push(points[i]);
		        }
		        else if (o > 0) {
		        	stack.push(points[i]);
		        }
		        else {
		                while (o <= 0 && stack.size() > 2) {
		                        stack.pop();
		                        top = (Point)stack.pop();
		        		    	second = (Point)stack.pop();
		                        o = Cross_product(second, top, points[i]);
		                        stack.push(second);
		        		        stack.push(top);
		                }
		                stack.push(points[i]);
		        }
		    }
		    System.out.println("Done");
			while(stack.size()>0) {
				Point pp = (Point)stack.pop();
				System.out.println(pp.x+" "+pp.y);
			}
		    //out.println(ans);                        
		    out.close();                                 
		    System.exit(0); 
	 }
	 
	 private static int Cross_product(Point p1, Point p2, Point p3) {
		 return (p2.x - p1.x)*(p3.y - p1.y) - (p3.x - p1.x)*(p2.y - p1.y);	
	 }
}

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.StringTokenizer;

/*
ID: kanishk1
LANG: JAVA
TASK: skate
*/

import java.util.*;
import java.io.*;

public class skate {
	 static char [][]arr;
	 static ArrayList list = new ArrayList();
	 static PrintWriter out;
	 public static void main (String [] args) throws IOException {
	    // Use BufferedReader rather than RandomAccessFile; it's much faster
	    BufferedReader f = new BufferedReader(new FileReader("skate.in"));
	                                                  // input file name goes above
	    out = new PrintWriter(new BufferedWriter(new FileWriter("skate.out")));
	    // Use StringTokenizer vs. readLine/split -- lots faster
	    StringTokenizer st = new StringTokenizer(f.readLine());
	    int R = Integer.parseInt(st.nextToken());   
	    int C = Integer.parseInt(st.nextToken());   
	    //System.out.println(R+" "+C);
	    arr = new char[R][C];
	    for(int i=0; i<R; i++) {
	    	arr[i] = f.readLine().trim().toCharArray();
	    }
	    list.add(pair(0,0));
	    doTask(0, 0);
	  }		  
	 
	 private static void doTask(int i, int j) {
		 //System.out.println(pair(i,j));
		 if(i==arr.length-1 && j==arr[0].length-1) {
			 //System.out.println("here"); 
			 out.println(printAnswer(list));                        
			 out.close();                                 
			 System.exit(0); 
		 }
		 if(isValid(i+1, j)) {
			 list.add(pair(i+1,j));
			 arr[i+1][j] = '@';
			 doTask(i+1,j);
			 arr[i+1][j] = '.';
			 list.remove(pair(i+1,j));
		 }
		 if(isValid(i-1, j)) {
			 list.add(pair(i-1,j));
			 arr[i-1][j] = '@';
			 doTask(i-1,j);
			 arr[i-1][j] = '.';
			 list.remove(pair(i-1,j));
		 }
		 if(isValid(i, j+1)) {
			 arr[i][j+1] = '@';
			 list.add(pair(i,j+1));
			 doTask(i,j+1);
			 arr[i][j+1] = '.';
			 list.remove(pair(i,j+1));
		 }
		 if(isValid(i, j-1)) {
			 arr[i][j-1] = '@';
			 list.add(pair(i,j-1));
			 doTask(i,j-1);
			 arr[i][j-1] = '.';
			 list.remove(pair(i,j-1));
		 }
		 return;
	 }
	 
	 private static boolean isValid(int i, int j) {
		 if(i<0 || j<0 || i>=arr.length || j>=arr[0].length) return false;
		 if(arr[i][j]!='.') return false;
		 return true;
	 }
	 
	 private static String pair(int i, int j) {
		 return (i+1)+" "+(j+1);
	 }
	 
	 private static String printAnswer(ArrayList list) {
		 String ans = "";
		 for(int i=0; i<list.size(); i++) {
			 ans+=list.get(i);
			 if(i!=list.size()-1) ans+="\n";
		 }
		 return ans;
	 }
}

$q = explode("&",$_SERVER["QUERY_STRING"]);
foreach ($q as $qi)
{
  if ($qi != "")
  {
    $qa = explode("=",$qi);
    list ($key, $val) = $qa;
    if ($val)
      $$key = urldecode($val);
  }
}
 
reset ($_POST);
while (list ($key, $val) = each ($_POST))
{
  if ($val)
    $$key = $val;
}

private boolean isPrime (int n)
{
   if (n<=1) return false;
   if (n==2) return true;
   if (n%2==0) return false;
   int m=(int)Math.round(Math.sqrt(n));

   for (int i=3; i<=m; i+=2)
      if (n%i==0)
         return false;

   return true;
}

public int GCD(int a, int b)
{
   if (b==0) return a;
   return GCD(b,a%b);
}