#include<iostream>
using namespace std;
#define ll long long
ll win(ll n, ll m, ll x, ll y){
    //int ans = 0;
    if((n*x) <= (m + y)){
        return n;
    }
    else{
        int noGotTicket = (m + y) / x;
        return noGotTicket;
    }
}

int main() {
    ll n, m, x, y;
    cin>>n>>m>>x>>y;
    ll ans = win(n, m, x, y);
    cout<<ans<<endl;
    return 0;
}