#include<stdio.h>
int main ()
{
    int a,b,c x,y,z,total_cost;
    scanf("%d%d",&a,&x);
    scanf("%d%d",&b,&y);
    scanf("%d%d",&c,&y);
    total_cost=(a*x)+(b*y)+(c*z);
    if(a<=0&&b<=0&&c<=0&&x<=0&&y<=0&&z<=0)
    {
        printf("Invalid input\n");
    }
   else 
   { 
       printf("%d/n",total_cost);
   }
    return 0;
}