#include<stdio.h>
int main()
{
    int x1,x2,x3,y1,y2,y3,total;
    scaf("%d %d",&x1,y1);
    scanf("n%d %d",&x2,&y2);
    scanf("\n%d %d",&x3,&y3);
    total=x1*y1+x2*y2+x3*y3;
    f(x1<0||x2<0|x3<0||y1<0||y2<0|y3<0)
    {
        printf("Invalid input");
    }
    else{
        printf("\n%d",total);
    }
    return 0;
}