char* g(unsigned int a) {
    char k[] = "0123456789ABCDEF";
    char r[sizeof (a)*2];
    int i = 0;
    while (a != 0) {
        r[i++] = k[a % 16];
        a /= 16;
    }
    while (i < 4) {
        r[i++] = '0';
    }
    char* t = malloc(i + 1);
    int j = 0;
    while (j < i) {
        t[j++] = r[i - 1 - j];
    }
    t[i] = 0;
    return t;
}