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

int main(void)
{
    char min, maj;
    char *p = NULL;

    for (min = 'a', maj = 'A'; maj <= 'Z'; min++, maj++)
    {
        p = (p == &min) ? &maj : &min;
        putchar(*p);
    }
    putchar('\n');
    return EXIT_SUCCESS;
}