#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 ans=0;
    
    while(s>0)
    {
        int cost;
        cost = p - ans*d;
        if(cost < m)
        {
            s = s - m;
        }
        else
        {
            s = s - cost;
        }
        ans++;
    }
    
    if(s < 0)
        --ans;
    
    return ans;
}

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;
}