#include <bits/stdc++.h>
#include <iostream>

using namespace std;



int howManyGames(int p, int d, int m, int s) {
    int count = 0;
    while (s-p >= 0){
        s = s-p ;
        count++;
        if(p-d >=m)
            p -= d;
        else
            p = 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;
}