#include<stdio.h>
int main()
{
    int ax, bx, ay, by, az, bz, total;
    scanf("%d %d",&ax, &bx);
    scanf("%d %d",&ay, &by);
    scanf("%d %d",&az, &bz);
    if(ax<0 || bx<0 || ay<0 || by<0 || az<0 || bz<0 )
    {
        printf("Invalid input");
    }
    else
    {
        total=(ax*bzx+(ay*by)+(az*bz);
        printf("%d",total);
    }
    return 0;
}