#include<bits/stdc++.h>
using namespace std;
int n,v[5],w[5],t,ans=0x3f3f3f,sum;
int main() {
	freopen("2.cpp","r",stdin);
	cin>>n;
	for(int i=1; i<=3; i++) {
		cin>>v[i]>>w[i];
		while(t<n){
			t+=v[i];
			sum+=w[i];
		}
		if(ans>sum) ans=sum;
		sum=0;
		t=0;
	}
	cout<<ans;
	return 0;
}