#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;
}