// editor4
#include<stdio.h>
int main(){
    int qx,qy,qz,px,py,pz;
    long total;
    if(scanf("%d %d",&qx,&px) !=2 || ("%d %d",&qy,&py) !=2 || ("%d %d",&qz,&pz) !=2  ){
        printf("Invalid input\n");
        return 1;
    }
    if(qx<0 || qz<0 ||qy<0||px<0||py<0||pz<0 ){
        printf("Invalid input\n");
        return 0;
    }
    total=(long)qx*px+(long)qy*py+(long)qz*pz;
    printf("%ld\n",total);
    return 0;
}