#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int sum = 0;
    // Return the number of games you can buy
    int i=0;
    while(sum<s)
    {
        int x = p - (i*d);
        if(x<=m)
            x = m;
        sum += x;
        i++;
       // if(sum>=s)
     }
    if(sum==s)
        return i;
    return i-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;
}