func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1e5 + 17;   int l1[N], r1[N], a[N], use[N];   map<int, bool> mt;   void dfs(int v, int l, int r) {     if (a[v] > l && a[v] < r) mt[a[v]] = 1;     if (l1[v] != -1) dfs(l1[v], l, min(r, a[v]));     if (r1[v] != -1) dfs(r1[v], max(l, a[v]), r);   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int n;     cin >> n;     for (int i = 1; i <= n; i++) {       cin >> a[i] >> l1[i] >> r1[i];       if (l1[i] != -1) use[l1[i]] = 1;       if (r1[i] != -1) use[r1[i]] = 1;     }     for (int i = 1; i <= n; i++)       if (use[i] == 0) dfs(i, -1, 1e9 + 1);     int ans = 0;     for (int i = 1; i <= n; i++)       if (mt[a[i]] == 0) ans++;     cout << ans << endl;   }   