#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 count=0, num=0,game=0,total=0;
    int sum=s;
    while(total<=sum)
    {
        game=p-d*num;
        if(game<=m)
           total+=m;
        else
            total+= game;
        num++;
        count++;
    }
    return count-1;
}

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;
}