#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int ag = 0,g=1,ga = 0;
    if(p < m)
        p = m;
    while(ga+p <= s){
        //cout<<p<<" ";
        ga += p;
        ag += 1;
        if(p-d >= m)
            p-=d;
        else
            p = m;
    }
    return ag;
}

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;
}