#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;
    while((s>0)&&(p>m))
    {
        s=s-p;
        p=p-d;
        if((s>=0))
        count++;
        else
        {
            p=m;
           // break;
        }
    }
    p=m;
    while(s>0)
    {
        
        s=s-m;
        if(s>=0)
            count++;
    }
    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;
}