// editor4
#include<stdio.h>
int main()
{
    int X,x;
    int Y,y;
    int Z,z;
    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<) || z<0)
    printf("Invalid input");
    else
    printf("%d",X*x+Y*y+Z*z);
    return 0;
    
}