#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
   int num = 0;
   int cost = 0;
   while(cost <= s)
   {   
       cost += p;
       num++;
       
       if(p - d <= m)
   {
       p = m;   
   }
       else
    {
       p = p - d; 
    }
      
       
   }
    if(cost>p)
        num--;
    
    return num;
}

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;
}