#include <unistd.h>

void rot13(char *str)
{
    int i;
    
    i = 0;
    while(str[i] != '\0')
    {
        if ((str[i] >= 'A' && str[i] <= 'M') || (str[i] >= 'a' && str[i] <= 'm'))
            str[i] += 13;
        else if((str[i] >= 'N' && str[i] <= 'Z') || (str[i] >= 'n' && str[i] <= 'z'))
            str[i] -=13;
        write(1,&str[i],1);
        i++;
    }
}

int main (int argc, char **argv)
{
    if (argc == 2)
        rot13(argv[1]);
    write(1, "\n",1);
}