y;main(z){int a[z=12];for(;z--;)scanf("%d",a+z);for(z=9;z--;)a[z]-=a[9+z%3];printf("%d",(a[3]*(a[7]*a[2]-a[1]*[8])+a[6]*(a[1]*a[5]-a[4]*a[2])+a[0]*(a[4]*a[8]-a[7]*a[5]))/6);}