#include<cstdio>
int main()
{
    int a[10],len,sum;
    for(int i=1;i<=6;i++)
        scanf("%d",&a[i]);
    len=a[1]+a[2]+a[6];
    sum=len*len-a[2]*a[2]-(len-a[2]-a[3])*(len-a[2]-a[3])-a[6]*a[6];
    printf("%d\n",sum);
    return 0;
}