#include 
#include 
#include 

char *ROT13(char *Data)
{
	int i;
	int Len = strlen(Data);

	if((Data == NULL) || (Len <= 0))
		return (char *)"Error Data is NULL!";

	for(i = 0; i <= Len; i++)
	{
		if(((int)toupper((int)Data[i]) >= 65) && ((int)toupper((int)Data[i]) <= 90))
		{
			Data[i] = (((toupper((int)Data[i])) + 13) % 90);

			if(Data[i] < 65)
				Data[i] += 65;
		}
	}

	return Data;
}