#include<stdio.h>
int main()
{
    int x,px,y,py,z,pz;
    long sum;
    
   if(scanf("%d %d",&x,&px) != 2 || scanf("%d %d",&y,&py) != 2 || scanf("%d %d",&z,&pz) != 2;
    
    {
       printf("Invalid input\n");  
    return 0;
    }
    
    if(x <0 || px<0 || y<0 || py<0 || z<0||pz<0 )
    {
    printf("Invalid input\n");  
    return 0;
    }
    sum=(x*px)+(y*py)+(z*pz);
    
    printf("%ld\n",sum);
    return 0;
    
}