#include <stdio.h>

int main()
{
	int A, B, C, D, ans = 0;

	if (scanf("%d %d %d %d", &A, &B, &C, &D) != 4) {
		return -1;
	}

	while (D > C + 1 && A > 0 && B - C >= 0) {
		D -= (C + 1);
		B -= C;
		A -= 1;
		ans++;
	}

	printf("%d", ans);

	return 0;
}