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


int main() {
    int p, d, m, s, c = 0, g = 0;
    cin >> p >> d >> m >> s;
    if(p <= s)
    {
        c += p;
        g += 1;
        //s -= p;
    }
    else
    {
        cout << 0;
        exit(0);
    }
    while(c <= s)
    {
        if(p - m < d)
            p -= (p-m);
        else if(p-m >= d)
            p -= d;
        c += p;
        g += 1;
        //s -= p;
    }
    cout << g-1;
    return 0;
}