#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 ans = -1;
    int dol = 0;
    int flag=0;
    while(dol<=s){
        if(flag==0){
            dol += p;
            p = p-d;
            flag=1;
            ans++;
        }else{
            if(p>=m){
                dol += p;
                 p = p-d;
                ans++;
            }else{
                dol += m;
                ans++;
            }
        }
    }
    return ans;
}

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;
}