#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int sum = p;
    int count = 0;
  
    while(sum<=s) {
      if(p-d>m) {
        sum += p-d;
        //cout<<p<<" ";
        p = p-d;
        
        count++;
      }
      else {
        sum += 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;
}