#include <bits/stdc++.h>
using namespace std;
const int ROOT = 0, MAXN = 100000;
const char WHITE = 0, GRAY = 1, BLACK = 2;
vector<int> graph[MAXN];
int n, m, a, b, i;
char k[MAXN] = {WHITE};
inline int dfs(const int& v = ROOT) {
  k[v] = GRAY;
  int i, t, p = -1;
  for (i = 0; i < (int)(graph[v].size()); i++)
    if (k[graph[v][i]] == WHITE) {
      t = dfs(graph[v][i]);
      if (t == -1) {
        if (p == -1)
          p = graph[v][i];
        else {
          printf("%d %d %d\n", p + 1, v + 1, graph[v][i] + 1);
          p = -1;
        }
      } else
        printf("%d %d %d\n", v + 1, graph[v][i] + 1, t + 1);
    } else if (k[graph[v][i]] == BLACK) {
      if (p == -1)
        p = graph[v][i];
      else {
        printf("%d %d %d\n", p + 1, v + 1, graph[v][i] + 1);
        p = -1;
      }
    }
  k[v] = BLACK;
  return p;
}
int main() {
  scanf("%d%d", &n, &m);
  if (m & 1) {
    printf("No solution\n");
    return 0;
  }
  for (i = 0; i < m; i++) {
    scanf("%d%d", &a, &b);
    a--;
    b--;
    graph[a].push_back(b);
    graph[b].push_back(a);
  }
  assert(dfs() == -1);
  return 0;
}
