#include <stdio.h>
//#include <stdlib.h>
#include <math.h>
//#define Conn(x,y) x##y
#define PI 3.141593
int main(void) 
{
    int arrange[3][3],num=0,price=99999;
    scanf("%d",&num);
    for (int i=0;i<3;i++)
    {
        scanf("%d %d",&arrange[i][0],&arrange[i][1]);
    }
    for(int j=0;j<3;j++)
    {
        arrange[j][2]= (int) ceil( ( 1.0*num ) / arrange[j][0] ) *arrange[j][1];
        
        if (price>arrange[j][2])
        {
            price=arrange[j][2];
        }
    }
    printf("%d",price);
}