#include <stdio.h>
int main()
{
    int qx, px, qy, py, qz, pz, total;
    scanf("%d %d", &qx,px);
    scanf("%d %d", &qy,py);
    scanf("%d %d", &qz,pz);
    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", total);
    }
    return 0;
}