1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
#include <stdio.h>

int
main()
{
    int ch;

    while ((ch = getchar()) != EOF) {
        if (ch == 'z') {
            ch = 'a';
        } else if (ch >= 'a' && ch <= 'z') {
            ++ch;
        }
        putchar(ch);
    }
}