#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 cost=p;
    int games=0;
    while(s>0)
    {s-=cost;
     if(cost-d>=m) cost-=d;
     else cost=m;
     if(s>=0) games++;
     
        
        
        
    }
    
    return games;
    
}

int main() {
    int p; //base price
    int d; //difference
    int m; //minimum
    int s; //rokda
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}