#include <bits/stdc++.h>

using namespace std;

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

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;
}