#include<iostream>
#include<cmath>
using namespace std;
int main(){
	double n,a,b,mina=9999999;
	cin>>n;
	for(int i=1;i<=3;i++){
		cin>>a>>b;
		mina=min(mina,ceil(n/a)*b);
	}
	cout<<mina;
	return 0;
}