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