#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 sum=0;
    
    int count=0;
    while(sum<=s)
    {
        if(p<m)
        {
            sum+=m;
        }
        else
        {
            sum+=p;
            p=p-d;
        }
        count++;
    }
    //cout<<sum<<endl;
    return count-1;
    
}

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;
}