#include <bits/stdc++.h>
using namespace std;
long long shu[5],yuan[5],n,t,s,minn=1000000;
int main()
{
	cin>>n;
	for(int i=1;i<=3;i++){
		cin>>shu[i]>>yuan[i];
	}
	for(int i=1;i<=3;i++){
		while(t<n){
			t+=shu[i];
			s++;
		}
		t=0;
		if(minn>s*yuan[i]) minn=s*yuan[i];
	}
	cout<<minn;
	return 0;
}