i,a[12];main(){for(;i<12;){scanf("%d", &a[i]);a[i++]-=a[i%3]*(i>2);}printf("%d\n",(a[3]*a[7]*a[11]+a[4]*a[8]*a[9]+a[5]*a[10]*a[6]-a[5]*a[7]*a[9]-a[8]*a[10]*a[3]-a[4]*a[11]*a[6])/6);}