Pair Calculate(int u) {
BigInteger ans;
Pair temp;
temp = new Pair();
if (g[u].size() == 0) {
temp.x = BigInteger.ONE;
temp.n = 1;
return temp;
}
if (g[u].size() == 1) {
temp = Calculate((int) g[u].get(0));
temp.n++;
return temp;
}
int p, q;
temp = Calculate((int) g[u].get(0));
ans = temp.x;
p = temp.n;
temp = Calculate((int) g[u].get(1));
ans = ans.multiply(temp.x);
q = temp.n;
ans = ans.multiply(C[p + q][p]);
temp.x = ans;
temp.n = p + q + 1;
return temp;
}
