#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 sum=0; int count=0;
    while(1){
        if(p>m) { if(sum+p<=s) count++; else break;  sum=sum+p; }
        else {
            if(sum+m<=s) count++; else break;  
            sum=sum+m;
        }
        if(p-d>m) p=p-d;
        else 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;
}