clexe.c

#include <queue>
#include <cstring>
#include <iostream>

using namespace std;

struct tree {
	int p;
	int left, right;
	tree() : p(-1) {}
	tree(int p, int left, int right) : p(p), left(left), right(right) {}
};

tree tr[10001];
int coldata[10001];
int col = 1;

int main(void) {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		int p, l, r;
		tr[p].left = l, tr[p].right = r;	// CL.exe 
		tr[l].p = p, tr[r].p = p;
 	}
	int root;
	for (int i = 1; i <= n; i++) {
		if (tr[i].p == -1) {
			root = i;
		}
	}

	cout << root << '\n';
	return 0;
}