#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 count = 0;
    int cp = p;
    if(s<cp){
        return 0;
    }
    while(cp>=m && s>=cp){
        count++;
        s-=cp;
        cp-=d;
    }
    if(cp<m){
        cp = m;
        while(s>=m){
            count++;
            s-=m;
        }
    }
    return count;
}

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;
}