#include<stdio.h>
int main()
{
    int qx, qy, qz, px, py, pz, total;
    if(scanf("%d\n %d\n %d\n %d\n %d\n %d\n",&qx, &px, &qy, &py, &qz, &pz));
    {
        printf("Invalid input");
        return 0;
    }
    
    else if(qx<0 || px<0 || qy<0 || py<0 || qz<0 || pz<0);
    {
        printf("Invalid input");
    }
    else 
    {
        total=(qx*px)+(qy*py)+(qz*pz);
        printf("%d\n",total);
    }
    return 0;
}