#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    
    int current_price = p;  int count = 0;
   while(s >= current_price){
       
       s = s - current_price;
       if(current_price - d >= m) 
           current_price = current_price - d;
       else
           current_price = m;
       
       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;
}