#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
#define dame { puts("-1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int a,b,c,d; cin >> a >> b >> c >> d;
    int ans = 0;
    while(true){
        if(a>0 && b>=c && d>=1+c){
            ans++;
            a--;
            b-=c;
            d-=1+c;
        }else{
            break;
        }
    }
    cout << ans << endl;
    return 0;
}