I didn't want to use a macro, so made 2 functions instead of 1!

include

int max (int a, int b); int max_of_four(int a, int b, int c, int d);

int main() { int a, b, c, d; scanf("%d %d %d %d", &a, &b, &c, &d); int ans = max_of_four(a, b, c, d); printf("%d", ans);

return 0;

}

int max_of_four(int a, int b, int c, int d) { return max(max(a, b), max(c, d)); }

int max (int a, int b) { if (a>b) return a; return b; }