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


int main() {
    int p, d, m, s;
    int count = 0;

    cin >> p;
    cin >> d;
    cin >> m;
    cin >> s;
    while (s - p >= 0) {
        s -= p;
        p = p - d > m ? p - d : m;
        count++;
    }    

    cout << count << endl;

    return 0;
}