Static void Main(string[] args)       
{           
String file = File.ReadAllText("input.txt");           
int s = Int32.Parse(file);           
int next = s + 1;           
int previous = s - 1;           
String outputString = String.Format("The next number for {0} is {1}.\r\nThe previous number for {0} is {2}.\r\n",s,next,previous);            File.WriteAllText("output.txt",outputString);       
 }