#include<stdio.h>
int main()
{
    int X,x;
    int Y,y;
    int Y,y;
    scanf("%d %d ",&X,&x);
    scanf("%d %d",&Y,&y);
    scanf("%d %d",&Z,&z);
    if(X<0 || x<0 || Y<0 || y<0 || Z<0 || z<0
    printf("Invalid input");
    else
    prinf("%d",X*x+Y*y+Z*z);
    return 0;