#include <iostream>
#include <cstdio>
#include <map>
#include <vector>

using namespace std;

typedef pair<int,int> pii;
#define mp make_pair
#define pb push_back

int n, m;

vector<int> g[100005];

map<pii,int> done, blocked;

int processed[100005];

void print(int a, int b, int c) {
	cout << a << ' ' << b << ' ' << c << '\n';
	done[mp(a,b)] = done[mp(b,a)] = true;
	done[mp(b,c)] = done[mp(c,b)] = true;
}

int cut(int v) {
	vector<int> adj;
	for(size_t i = 0; i < g[v].size(); i++) {
		int u = g[v][i];
		if(!blocked[mp(v,u)]) {
			blocked[mp(v,u)] = blocked[mp(u,v)] = true;
			adj.pb(u);
		}
	}
	
	int sz = adj.size();
	for(int i = 0; i < sz; i++) {
		int u = adj[i];
		if(!processed[u]) {
			int w = cut(u);
			if(w != 0) {
				print(v,u,w);
			}
		}
	}
	
	int u = 0;
	for(int i = 0; i < sz; i++) {
		int curr = adj[i];
		if(!done[mp(v,curr)]) {
			if(u==0) {
				u = curr;
			} else {
				print(u,v,curr);
				u = 0;
			}
		}
	}
	
	processed[v] = true;
	return u;
}

int main() {
	ios_base::sync_with_stdio(false);
	
	cin >> n >> m;
	
	if(m%2==1) {
		cout << "No solution" << endl;
		return 0;
	}
	
	for(int i = 0; i < m; i++) {
		int a, b; cin >> a >> b;
		g[a].pb(b);
		g[b].pb(a);
	}
	
	cut(1);
}