#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s)
{
    int i,j,l;
    int sum=0;
    for(i=0;sum<=s;i++)
    {
      
        sum=sum+p;
        if(p-d>=m)
        {
            p=p-d;
        }
        
        else
            p=m;
       
    }
    return i-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;
}