#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 i,c=0,sum=0;
    
    while(sum<=s)
    {
        if(p>m)
        {
            sum+=p;
            p-=d;
        }    
        else
           sum+=m;
        c++;           
    }    
    
    return c-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;
}