#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
int par[maxn], hi[maxn], n, m;
vector<int> v[maxn], bak[maxn];
bool mark[maxn], markb[maxn];
void dfs(int x) {
  vector<int> ans;
  mark[x] = 1;
  for (int i = 0; i < v[x].size(); i++) {
    int child = v[x][i];
    if (!mark[child]) {
      hi[child] = hi[x] + 1;
      par[child] = x;
      dfs(child);
      if (bak[child].size()) {
        cout << bak[child][0] << ' ' << child << ' ' << x << endl;
        bak[child].pop_back();
        markb[child] = 1;
      } else if (!markb[child])
        ans.push_back(child);
    } else if (hi[child] < hi[x] and child != par[x])
      bak[x].push_back(child);
  }
  while (ans.size() > 1) {
    cout << ans[ans.size() - 1] << ' ' << x << ' ' << ans[ans.size() - 2]
         << endl;
    markb[ans[ans.size() - 1]] = 1;
    markb[ans[ans.size() - 2]] = 2;
    ans.pop_back();
    ans.pop_back();
  }
  while (bak[x].size() > 1) {
    cout << bak[x][bak[x].size() - 1] << ' ' << x << ' '
         << bak[x][bak[x].size() - 2] << endl;
    bak[x].pop_back();
    bak[x].pop_back();
  }
  if (ans.size() and bak[x].size()) {
    cout << ans[ans.size() - 1] << ' ' << x << ' ' << bak[x][bak[x].size() - 1]
         << endl;
    markb[ans[ans.size() - 1]] = 1;
    ans.pop_back();
    bak[x].pop_back();
  }
  if (ans.size() and !bak[x].size()) {
    cout << ans[ans.size() - 1] << ' ' << x << ' ' << par[x] << endl;
    markb[x] = 1;
    markb[ans[ans.size() - 1]] = 1;
    ans.pop_back();
  }
  if (!ans.size() and bak[x].size()) {
    cout << bak[x][bak[x].size() - 1] << ' ' << x << ' ' << par[x] << endl;
    bak[x].pop_back();
    markb[x] = 1;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  int a, b;
  for (int i = 1; i <= m; i++) {
    cin >> a >> b;
    v[a].push_back(b);
    v[b].push_back(a);
  }
  if (m & 1)
    cout << "No solution";
  else
    dfs(1);
}
