#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int i;
    for (i=0; ;i++){
        int d_tmp = d*i;
        int p_tmp = p - d_tmp;
        if ((p_tmp<m))
            p_tmp=m;
        s-=p_tmp;
        if(s<0){
            break;
        }
    }
    return i;
}

int main() {
    int p;
    int d;
    int m;
    int s;//20 3 6 8
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}