#!/usr/local/bin/tcc -run
#include <stdio.h>
int main(void)
{
    char *str = "aaAbbBccCDeeEffFgggG";
    char *p1, *p2;
    p1 = p2 = str;
    while (*p1!= '\0') {
        if ('A' <= *p1 && *p1 <= 'Z') {
            *p2 = *p1;
            p2++;
        }
        p1++;
    }
    *p2 = '\0';
    printf("%s\n", str);
    return 0;
}