#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>



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