#include <stdio.h>

int main() {
    const char *alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int i = 0;
    int len = 0;
    int maxlen = 1;

    while (maxlen < 52) {
        putchar(alpha[i++]);
        i %= 26;
        if (++len >= maxlen) {
            putchar('\n');
            len = 0;
            maxlen += 2;
        }
    }
}