// 3 lines

class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
if((p->val<=root->val && q->val>=root->val)||(p->val>=root->val && q->val<=root->val)) return root;
if(p->val > root->val && q->val > root->val) return lowestCommonAncestor(root->right,p,q);
if(p->val < root->val && q->val < root->val) return lowestCommonAncestor(root->left,p,q);
}
};