#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int p1=p;
    int cnt=0;
    while(s-p1>=0){
        s-=p1;
        if(p1-d>=m)
        p1=p1-d;
        else
        p1=m;
        cnt++;
        
    }
    return cnt;
}

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;
}