#include<bits/stdc++.h>

#define LL long long

#define fi first

#define se second

#define mk make_pair

#define PLL pair<LL, LL>

#define PLI pair<LL, int>

#define PII pair<int, int>

#define SZ(x) ((int)x.size())

#define ull unsigned long long

using namespace std;

const int N = 1e5 + ;

const int inf = 0x3f3f3f3f;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int mod = 1e9 + ;

const double eps = 1e-;

const double PI = acos(-);

int n, m;

bool vis[N];

vector<int> G[N];

queue<int> que[N];

vector<pair<int, PII>> ans;

void dfs(int u, int fa) {

    vis[u] = true;

    for(auto& v : G[u]) {

        if(!vis[v]) {

            dfs(v, u);

        } else if(v != fa && vis[v]) {

            que[v].push(u);

        }

    }

    while(SZ(que[u]) >= ) {

        int x = que[u].front(); que[u].pop();

        int y = que[u].front(); que[u].pop();

        ans.push_back(mk(x, mk(u, y)));

    }

    if(SZ(que[u])) {

        if(!fa) {

            puts("No solution");

            exit();

        }

        int x = que[u].front(); que[u].pop();

        ans.push_back(mk(x, mk(u, fa)));

    } else {

        que[fa].push(u);

    }

}

int main() {

    scanf("%d%d", &n, &m);

    for(int i = ; i <= m; i++) {

        int u, v; scanf("%d%d", &u, &v);

        G[u].push_back(v);

        G[v].push_back(u);

    }

    if(m & ) puts("No solution");

    else {

        dfs(, );

        for(auto& t : ans)

            printf("%d %d %d\n", t.fi, t.se.fi, t.se.se);

    }

    return ;

}

/*

*/