public class ROT13
{

    public ROT13()
    {
    }

    public String encrypt( String s )
    {
        
        // Create array
        int ar[] = new int[ s.length() ];
        
        for( int i = 0; i < s.length(); i++ ){
            ar[i] = s.charAt( i );
        }
        
        
        // ROT13
        for( int i = 0; i < s.length(); i++ ){
         
            if( ar[i] >= 'a' && ar[i] <= 'z' ){
                int j = ar[i] + 13;
            
                if( j > 'z' ){
                    j = j - 26;
                }
            
                ar[i] = j;
            }
            else if( ar[i] >= 'A' && ar[i] <= 'Z' ){
                int j = ar[i] + 13;
            
                if( j > 'Z' ){
                    j = j - 26;
                }
            
                ar[i] = j;
            }

            
        }
        
        
        // Convert to array of bytes
        byte arb[] = new byte[ s.length() ];
        
        for( int i = 0; i < s.length(); i++ ){
            arb[i] = (byte)ar[i];
        }
        
        // Convert back to a String
        String s2 = new String( arb );
     
        return s2;
        
    }
}