#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    
    int last=p;
    int ans=0;
    bool first=true;
    while(s>0)
    {
        if(last<=m && first==false)
        {
            s=s-m;
            first=false;
        }
        else 
        {
            s=s-last;
            last=last-d;
            first=false;
        }
        if(s>=0)
            ans++;
    }
    return ans;
    
}

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;
}