#include <bits/stdc++.h>
const int N = 1e6 + 50;
int n, m, w[N], c[N], s[N];
bool vis[N];
std::vector<std::pair<int, int> > G[N];
template <int T>
struct fast_io {
  char p[T], q[T], *p1, *p2, *q1, *q2;
  fast_io() {
    p1 = p2 = p;
    q1 = q, q2 = q + T;
  }
  inline char gc() {
    return p1 == p2 && (p2 = (p1 = p) + fread(p, 1, T, stdin), p1 == p2)
               ? EOF
               : *p1++;
  }
  inline void pc(char c) {
    if (q1 == q2) q2 = (q1 = q) + fwrite(q, 1, T, stdout);
    *q1++ = c;
  }
  ~fast_io() { fwrite(q, 1, q1 - q, stdout); }
};
fast_io<1 << 20> io;
inline int64_t read() {
  int64_t res = 0, neg = 1;
  char ch;
  do {
    ch = io.gc();
    if (ch == '-') neg = -1;
  } while (ch < 48 || ch > 57);
  do res = res * 10 + ch - 48, ch = io.gc();
  while (ch >= 48 && ch <= 57);
  return res * neg;
}
inline void put(int64_t x) {
  if (x < 0) io.pc('-'), x = -x;
  if (x >= 10) put(x / 10);
  io.pc(48 + x % 10);
}
inline void output(int64_t x, char ch = ' ') {
  put(x);
  io.pc(ch);
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= m; ++i) {
    int u = read(), v = read();
    if (u < v) std::swap(u, v);
    G[u].emplace_back(v, i);
    w[i] = 1;
    ++s[u], ++s[v];
  }
  for (int x = 1; x <= n; ++x) {
    for (auto &[y, i] : G[x]) {
      if (!c[y]) {
        ++c[y];
        --w[i];
        --s[x];
      }
      vis[s[y]] = true;
    }
    int &cur = s[x];
    for (auto &[y, i] : G[x]) {
      if (!vis[cur]) break;
      --c[y];
      ++w[i];
      ++cur;
    }
    for (auto &[y, i] : G[x]) vis[s[y]] = false;
  }
  std::vector<int> res;
  for (int i = 1; i <= n; ++i)
    if (c[i]) res.push_back(i);
  printf("%d\n", res.size());
  for (int x : res) printf("%d ", x);
  putchar('\n');
  for (int x = 1; x <= n; ++x)
    for (auto &[y, i] : G[x]) printf("%d %d %d\n", x, y, w[i]);
  return 0;
}
