#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 t = s;
    int count = 0;
    int r = 0;
    if(s<p) return count;
    while(s>0){
        if(p-r > m){
            if(s < p-r){
                return count;
            }
            count++;
            s = s-p+r;
            r = r+d;
        }
        else{
            if(s>=m){
                count++;
                s = s-m;
            }
            else{
                return count;
            }
        }
       // r = r+d;
    }
    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;
}