int height(Node* root)
{
if (root == 0) {return 0;}
int a, b, c;
a = 0; b = 0; c = 0;
if (root->one) {a=height(root->one)+1;}
if (root->two) {b=height(root->two)+1;}
if (root->three){c=height(root->three)+1;}
return max(a,b,c);