#include<bits/stdc++.h>
using namespace std;
 
using ll=long long;
using pp=pair<int,int>;
#define sr string 
#define vc vector
#define db double
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define pb push_back
#define all(v) v.begin(),v.end()
#define pque priority_queue
#define bpc(a) __builtin_popcount(a)
int main(){
	ll h,w,ah,aw,bh,bw;cin>>h>>w>>ah>>aw>>bh>>bw;
	ll ans=h+w;
	for(ll i=0;i<h+w;i++){
		ll x=min(h,i*ah);
		ll r=h*w-i*bh;
		if(r<=0){
			ans=min(ans,i);
			continue;
		}
		ll wa=0,ac=h+w;
		while(ac-wa>1){
			ll m=(ac+wa)/2;
			ll now=min(w,aw*m)*x+m*bw;
			if(now>=r)ac=m;
			else wa=m;
		}
		ans=min(ans,ac+i);
	}
	cout<<ans;
}