#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 cnt = 0;
    int c = p;
    while(s>=0){
       if(s>=c){
      
           s = s - c;
           c = max(m, c - d);
           cnt++;
       }
        else
        {
            break;
        }
    }
return cnt;
}

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;
}