#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


#define BUFFER_LEN 4096

char rot13(char c)
{
    if ((c >= 'a' && c <= 'm') || (c >= 'A' && c <= 'M'))
        return c + 13;
    else if ((c >= 'n' && c <= 'z') || (c >= 'N' && c <= 'Z'))
        return c - 13;
    return c;
}


int main(int argc, char *argv[])
{
    char *buf = malloc(BUFFER_LEN);
    while (1) {
        ssize_t br = read(fileno(stdin), buf, BUFFER_LEN);
        if (br == 0)
            break;
        for (int i = 0; i < br; i++) {
            printf("%c", rot13(buf[i]));
        }
    }

    return 0;
}