#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 cnt=0;
    while(s>=m or s>=p){
        if(s >= m and p <= m)
            s-=m, cnt+=1;
        else if (s >= p)
            s-=p, p=max(p-d,m), cnt+=1;
        else break;
    }
    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;
}