#include <iostream>
#include <math.h>
using ll = long long;
#define MOD 1000000007
using namespace std;

int main(){
    int A, B, C, D,cnt = 0;
    cin >> A >> B >> C >> D;
    while (A) {
        if (B>=C && D>=C+1) {
            A--;
            B-=C;
            D-=C+1;
            cnt++;
        }
        else {
            break;
        }
    }
    cout << cnt << endl;
    return 0;
}