#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 x=p,f=0,sum=0;
    for(int i=0;;i++)
    {
       sum+=(x);
        
        x-=d;
        if(x<=m)
            x=m;
        if(sum>s)
            break;
        f++;
        
    }
    return f;
}

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;
}