#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    long long int ans=0;
    long long int temp=s;
    long long int price=p;
    while(price>m)
    {
        temp = temp-price;
        if(temp<0)
            break;
        price-=d;
        ans++;
    }
    if(temp>=0)
    ans+=temp/m;
    
    return ans;
    
        
    // Return the number of games you can buy
}

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;
}