ONEGCD

#include<bits/stdc++.h>
using namespace std;
/// from HUNG MINE with love <3
int n, m, d[100001], k = 1;
vector <int> a[100001];
void bfs () {
      queue <int> q;
      q.push (1);
      while (q.size ()) {
            int u = q.front ();
            q.pop ();
            for (auto v : a[u]) {
                  if (d[v] > 0) {
                        -- d[v];
                        -- d[u];
                        cout << u << " " << v << " " << k << "\n";
                        ++ k;
                        q.push (v);
                  }
            }
      }
}
int main () {
      if (fopen ("test.inp", "r")) {
            freopen ("test.inp", "r", stdin);
      }
//      else {
//            freopen ("ONEGCD.inp", "r", stdin);
//            freopen ("ONEGCD.out", "w", stdout);
//      }

      ios_base :: sync_with_stdio (0);
      cin.tie (0);
      cout.tie (0);
      cin >> n >> m;
      for (int i = 1; i <= m; ++ i) {
            int x, y;
            cin >> x >> y;
            a[x].push_back (y);
            a[y].push_back (x);
            ++ d[x];
            ++ d[y];
      }
      for (int i = 1; i <= n; ++ i) {
            sort (a[i].begin (), a[i].end ());
      }
      bfs ();
}