#include <bits/stdc++.h>

using namespace std;

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