造福后人

#include <iostream>
#include <algorithm>
#include <vector>
#include <random>
using namespace std;
#define ll long long
#define pii pair<int, int>
mt19937 ci(time(0));
const int N = 400005;
inline int C(int n) {return ci() % n + 1;}
vector<int> e[N];
int leaf = 0, n, m;
int to[N];
vector<pair<int, int> > p;
void dfs(int u, int fa) {
    bool flag = 0;
    for (int v : e[u]) if (v != fa) {
        if (!to[u]) to[u] = ++n;
        dfs(v, u);
        flag = 1;
    }
    if (fa == 0) return;
    p.push_back({fa, u});
    if (!to[u]) {
        p.push_back({to[fa], u});
    } else {
        p.push_back({to[fa], to[u]});
    }
}
int main() {
    freopen("1.in", "w", stdout);
    n = 500; // 这个树 T 的节点个数在这里修改
    for (int i = 2; i <= n; i++) {
        int j = C(i - 1);
        e[j].push_back(i);
    }
    dfs(1, 0);
    m = p.size();
    printf("%d %d\n", n, m);
    for (auto x : p) {
        printf("%d %d\n", x.first, x.second);
    }
    return 0;
}