#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int res=p;
    int cnt=0;
    while(res>m&&s>0)
    {
        cnt++;
        s=s-res;
        res-=d;
    }
    if(s<=0)
        return cnt-1;
    else
    {
        return cnt+s/m;
    }
}

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;
}