#include<stdio.h>
int main()
{
    int a,b,c,d,e,f,h;
    scanf("%d %d \n%D %d \n%d %d",&a, &b, &c, &d, &e,&f);
    h = (a*b)+(c*d)+(e*f);
    if(a<0 || b<0 || c<0 || d<0 || e<0 || f<0)
    {
        printf("Invalid input");
    }
    else
    {
        printf("%d",h);
    }
}