#include <bits/stdc++.h>
using namespace std;
int n, m;
vector<int> g[100005];
int vis[100005];
vector<vector<int> > r;
bool dfs(int x, int f) {
  vis[x] = 1;
  int k = -1;
  for (int y : g[x]) {
    if (y == f) continue;
    if (vis[y] > 0 || !vis[y] && !dfs(y, x)) {
      if (k < 0)
        k = y;
      else
        r.push_back({k, x, y}), k = -1;
    }
  }
  vis[x] = -1;
  if (k >= 0) {
    r.push_back({k, x, f});
    return true;
  }
  return false;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int _ = 0, ThxDem = m; _ < ThxDem; ++_) {
    int x, y;
    scanf("%d%d", &x, &y);
    x--;
    y--;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  for (int i = 0, ThxDem = n; i < ThxDem; ++i)
    if (!vis[i] && dfs(i, -1)) {
      puts("No solution");
      return 0;
    }
  for (auto v : r) printf("%d %d %d\n", v[0] + 1, v[1] + 1, v[2] + 1);
  return 0;
}
