#include<cstdio>
int main() {
    int ve, me, mul, lim;
    scanf("%d %d %d %d", &ve, &me, &mul, &lim);
    int ans = 0;
    for (int i = ve; i >= 0; --i) {
        for (int j = me; j >= 0; --j) {
            if (mul * i > j) break;
            if (i + j > lim) continue;
            ans = (ans < i ? i : ans);
        }
    }
    printf("%d\n", ans);
}