#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const int intmax = 0x3f3f3f3f;
const long long lldmax = 0x3f3f3f3f3f3f3f3fll;
double eps = 1e-6;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T checkmod(T n, T m) {
  return (n % m + m) % m;
}
inline int rand(int a, int b) {
  if (a >= b) return a;
  return rand() % (b - a) + a;
}
template <class T>
inline T lcm(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <class T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <class T>
inline T euclid(T a, T b, T &x, T &y) {
  if (a < 0) {
    T d = euclid(-a, b, x, y);
    x = -x;
    return d;
  }
  if (b < 0) {
    T d = euclid(a, -b, x, y);
    y = -y;
    return d;
  }
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    T d = euclid(b, a % b, x, y);
    T t = x;
    x = y;
    y = t - (a / b) * y;
    return d;
  }
}
template <class T>
inline vector<pair<T, int> > factorize(T n) {
  vector<pair<T, int> > R;
  for (T i = 2; n > 1;) {
    if (n % i == 0) {
      int C = 0;
      for (; n % i == 0; C++, n /= i)
        ;
      R.push_back(make_pair(i, C));
    }
    i++;
    if (i > n / i) i = n;
  }
  if (n > 1) R.push_back(make_pair(n, 1));
  return R;
}
template <class T>
inline bool isPrimeNumber(T n) {
  if (n <= 1) return false;
  for (T i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
template <class T>
inline T eularFunction(T n) {
  vector<pair<T, int> > R = factorize(n);
  T r = n;
  for (int i = 0; i < R.size(); i++) r = r / R[i].first * (R[i].first - 1);
  return r;
}
template <class T>
inline int dblcmp(T a, const T b) {
  a -= b;
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
template <class T>
inline int sgn(T a) {
  return a > eps ? 1 : (a < -eps ? -1 : 0);
}
const int N = 110000;
struct NODE {
  int v, nxt;
} edge[N * 2];
int ept = 0;
int node[N];
int ans[N][3], top = 0;
void addEdge(int a, int b) {
  edge[ept].nxt = node[a];
  edge[ept].v = b;
  node[a] = ept++;
}
int mark[N];
int me[N];
int dfs(int r, int p) {
  if (mark[r] == 1) return -1;
  mark[r] = 1;
  int last = -1;
  int cur;
  for (int i = node[r]; i != -1; i = edge[i].nxt) {
    if (me[i / 2]) continue;
    me[i / 2] = 1;
    cur = dfs(edge[i].v, i);
    if (cur != -1) {
      ans[top][0] = r;
      ans[top][1] = edge[i].v;
      ans[top][2] = cur;
      top++;
    } else if (last == -1) {
      last = edge[i].v;
    } else {
      ans[top][0] = last;
      ans[top][1] = r;
      ans[top][2] = edge[i].v;
      top++;
      last = -1;
    }
  }
  return last;
}
int main() {
  memset(node, 0xff, sizeof(node));
  int n, m;
  int a, b;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < m; ++i) {
    scanf("%d%d", &a, &b);
    addEdge(a, b);
    addEdge(b, a);
  }
  bool yes = true;
  for (int i = 1; i <= n; ++i) {
    if (dfs(i, -1) != -1) {
      yes = false;
      break;
    }
  }
  if (yes) {
    for (int i = 0; i < top; ++i) {
      printf("%d %d %d\n", ans[i][0], ans[i][1], ans[i][2]);
    }
  } else {
    puts("No solution");
  }
  return 0;
}
