func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   inline bool chmax(T &a, T b) {     if (a < b) {       a = b;       return true;     }     return false;   }   template <class T>   inline bool chmin(T &a, T b) {     if (a > b) {       a = b;       return true;     }     return false;   }   const long long INF = 1e18;   int N, K;   vector<int> vertex;   vector<int> d[200];   set<pair<int, int>> st;   vector<int> g[30000];   int dist[200][30000];   void dfs(int idx, int now, int from) {     for (auto to : g[now]) {       if (to == from) continue;       dist[idx][to] = dist[idx][now] + 1;       dfs(idx, to, now);     }   }   set<int> appear;   map<int, vector<pair<int, int>>> children;   struct UnionFind {     vector<int> par;     vector<int> rank;     vector<long long> Size;     UnionFind(int n = 1) { init(n); }     void init(int n = 1) {       par.resize(n + 1);       rank.resize(n + 1);       Size.resize(n + 1);       for (int i = 0; i <= n; ++i) par[i] = i, rank[i] = 0, Size[i] = 1;     }     int root(int x) {       if (par[x] == x) {         return x;       } else {         int r = root(par[x]);         return par[x] = r;       }     }     bool issame(int x, int y) { return root(x) == root(y); }     bool merge(int x, int y) {       x = root(x);       y = root(y);       if (x == y) return false;       if (rank[x] < rank[y]) swap(x, y);       if (rank[x] == rank[y]) ++rank[x];       par[y] = x;       Size[x] += Size[y];       return true;     }     long long size(int x) { return Size[root(x)]; }   };   int match[30000];   int TL = 2980;   int main() {     cin.tie(0);     ios::sync_with_stdio(false);     auto start = chrono::steady_clock::now();     int nowtimer;     cin >> N >> K;     vertex.resize(K, -1);     for (int k = 0; k < K; k++) {       d[k].resize(N);       for (int i = 0; i < N; i++) {         cin >> d[k][i];         if (d[k][i] == 0) {           if (vertex[k] != -1) {             cout << -1 << endl;             return 0;           } else {             vertex[k] = i;           }         }       }       if (vertex[k] == -1) {         cout << -1 << endl;         return 0;         ;       }       appear.insert(vertex[k]);     }     for (int k = 1; k < K; k++) {       int mini = d[0][vertex[k]];       vector<int> v(mini + 1, -1);       for (int i = 0; i < N; i++) {         if (d[0][i] + d[k][i] < mini) {           cout << -1 << endl;         }         if (d[0][i] + d[k][i] == mini) {           if (v[d[0][i]] != -1) {             cout << -1 << endl;             return 0;             ;           }           v[d[0][i]] = i;         }       }       for (int i = 0; i <= mini; i++) {         if (v[i] == -1) {           cout << -1 << endl;           return 0;           ;         }       }       for (int i = 0; i < mini; i++) {         int a = v[i];         int b = v[i + 1];         if (a > b) swap(a, b);         st.insert({a, b});       }     }     UnionFind uni(N);     for (auto tmp : st) {       if (!uni.merge(tmp.first, tmp.second)) {         cout << -1 << endl;         return 0;       } else {         g[tmp.first].push_back(tmp.second);         g[tmp.second].push_back(tmp.first);         appear.insert(tmp.first);         appear.insert(tmp.second);       }     }     vector<pair<vector<int>, int>> mp;     for (int i = 0; i < N; i++) {       if (appear.find(i) == appear.end()) continue;       vector<int> v(K);       int mini = 1e9;       for (int j = 0; j < K; j++) {         v[j] = d[j][i];         chmin(mini, v[j]);       }       for (int j = 0; j < K; j++) {         v[j] -= mini;       }       mp.push_back({v, i});     }     mp.push_back({{999999999}, -1});     sort(mp.begin(), mp.end());     vector<pair<vector<int>, int>> sub;     for (int i = 0; i < N; i++) {       if (appear.find(i) != appear.end()) continue;       vector<int> v(K);       int mini = 1e9;       for (int j = 0; j < K; j++) {         v[j] = d[j][i];         chmin(mini, v[j]);       }       for (int j = 0; j < K; j++) {         v[j] -= mini;       }       sub.push_back({v, i});     }     sort(sub.begin(), sub.end());     int idx = 0;     if ((nowtimer = chrono::duration_cast<chrono::milliseconds>(                         chrono::steady_clock::now() - start)                         .count()) > TL) {       assert(0);     }     for (int i = 0; i < sub.size(); i++) {       if ((nowtimer = chrono::duration_cast<chrono::milliseconds>(                           chrono::steady_clock::now() - start)                           .count()) > TL) {         return 0;       }       while (mp[idx].first < sub[i].first) idx++;       if (mp[idx].first == sub[i].first) {         match[sub[i].second] = mp[idx].second;       } else {         cout << -1 << endl;         return 0;       }     }     for (int i = 0; i < N; i++) {       if (appear.find(i) != appear.end()) continue;       int p = match[i];       int len = d[0][i] - d[0][p];       if (len <= 0) {         cout << -1 << endl;         return 0;       }       children[p].push_back({len, i});     }     for (int i = 0; i < N; i++) {       if (children[i].empty()) continue;       auto v = children[i];       sort(v.begin(), v.end());       if (v[0].first != 1) {         cout << -1 << endl;         return 0;       }       int Last = i;       st.insert({i, v[0].second});       g[Last].push_back(v[0].second);       g[v[0].second].push_back(Last);       for (int i = 1; i < v.size(); i++) {         if (v[i].first > v[i - 1].first + 1) {           cout << -1 << endl;           return 0;         } else if (v[i].first == v[i - 1].first) {           st.insert({Last, v[i].second});           g[Last].push_back(v[i].second);           g[v[i].second].push_back(Last);         } else {           Last = v[i - 1].second;           st.insert({Last, v[i].second});           g[Last].push_back(v[i].second);           g[v[i].second].push_back(Last);         }       }     }     for (int i = 0; i < K; i++) {       dfs(i, vertex[i], -1);       for (int j = 0; j < N; j++) {         if (dist[i][j] != d[i][j]) {           cout << -1 << endl;           return 0;         }       }     }     for (auto e : st) {       cout << e.first + 1 <<     << e.second + 1 << endl;     }     return 0;   }   