#include<stdio.h>
int main(){
    int a,b,c;
    int x,y,z;
    int n1;
    if(scanf("%d %d",&a,&x)!=2 || scanf("%d %d",&b,&y)!=2 || scanf("%d %d",&c,&z)!=2)
    {
        printf("Invalid input");
    }
    if(a<0 || b<0 || c<0 || x<-1000|| x>1000 || y<-1000 ||y>1000 || z<-1000 || z>1000)
    {
       printf("Invalid input"); 
    }
    else{
        n1=a*x+b*y+c*z;
        printf("%d\n",n1)
    }
    return 0;
}