#include <cstdio>
#include <iostream>
using namespace std;
int main(){
	int t1,t2,t3,m1,m2,m3,s1,s2,s3,p;
	scanf("%d",&p);
	scanf("%d%d%d%d%d%d",&t1,&m1,&t2,&m2,&t3,&m3);
	s1 = p % t1 == 0 ? p / t1 * m1 : (p / t1 + 1) * m1;
	s2 = p % t2 == 0 ? p / t2 * m1 : (p / t2 + 1) * m2;
	s3 = p % t3 == 0 ? p / t3 * m1 : (p / t3 + 1) * m3;
	printf("%d",min(min(s1,s2),s3));
	return 0;
}