#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
 int su=0,count=0;
 
   
      while(su<=s)
      {    count++;
          su+=p;
       if(p>m)
       {
          p=p-d;
       }
       if(m>p)
       {
p=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;
}