AC

#include <iostream>
#include <vector>

using namespace std;

struct Node {

int value;
int left;
int right;

};

vector tree; int target; int count = 0; int result = 0;

void inorder(int root) {

if (root == 0) {
    return;
}
inorder(tree[root].left);
count++;
if (tree[root].value == target) {
    result = count;
    return;
}
inorder(tree[root].right);

}

int main() {

int n;
cin >> n >> target;
tree.resize(n + 1); // 使用1-based索引
for (int i = 1; i <= n; i++) {
    cin >> tree[i].value >> tree[i].left >> tree[i].right;
}
inorder(1);
cout << result << endl;
return 0;

}