#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int p, d, m, s;
    cin >> p >> d >> m >> s;
    int counter = 0;
    while (s >= p){
        s -= p;
        if (p >= m+d)
            p -= d;
        else
            p = m;
        counter++;
    }
    cout << counter << endl;
    return 0;
}