public static string RailFenceCipher(string input){
			// b.t.w we only use two rails
			string rail1 = "";
			string rail2 = "";
			char[] arry = input.ToCharArray();
			bool top = true;
			foreach(char ch in arry){
				if(top == true)
					rail1 += ch.ToString();
				else
					rail2 += ch.ToString();
				top = !top;
			}
			return rail1 + rail2;
		}
		public static string DeRailFenceCipher(string input){
			// b.t.w we only use two rails
			string rail1 = input.Substring(0,input.Length / 2);
			string rail2 = input.Substring(input.Length / 2);
			int r1 = 0;
			int r2 = 0;
			string o = "";
			bool top = true;
			while(o.Length != input.Length){
				if(top == true){
					o += rail1.Substring(r1, 1);
					r1 ++;
				}
				else{
					o += rail2.Substring(r2, 1);
					r2 ++;
				}
				top = !top;
			}
			return o;
		}

#!/bin/bash
read VARIABLE
if [ $VARIABLE -eq $VARIABLE 2> /dev/null ]; then
echo $VARIABLE is a number
else
echo $VARIABLE is not a number
fi