#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 count = 0, p1 = p;
    while(p1 >= m && s >= p1){
        count ++;
        s -= p1;
        p1 -= d;
    }
    if(p1 < m){
        p1 = m;
        count += s / m;
    }
    return count;
}

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