#include <bits/stdc++.h>
using namespace std;
long long modexp(long long base, long long exp) {
  if (exp == 1)
    return base;
  else if (exp == 0)
    return 1;
  else {
    if (exp % 2 == 0) {
      long long base1 = pow(modexp(base, exp / 2), 2);
      if (base1 >= 1000000007)
        return base1 % 1000000007;
      else
        return base1;
    } else {
      long long ans = (base * pow(modexp(base, (exp - 1) / 2), 2));
      if (ans >= 1000000007)
        return ans % 1000000007;
      else
        return ans;
    }
  }
}
long long gcd(long long a, long long b) {
  if (!a) return b;
  return gcd(b % a, a);
}
long long mexp(long long a, long long b) {
  long long ans = 1;
  a %= 1000000007;
  while (b) {
    if (b & 1) ans = ans * a % 1000000007;
    b >>= 1;
    a = a * a % 1000000007;
  }
  return ans;
}
long long int phi(long long x) {
  long long int ret = 1, i, pow;
  for (i = 2; x != 1; i++) {
    pow = 1;
    if (i > sqrt(x)) break;
    while (!(x % i)) {
      x /= i;
      pow *= i;
    }
    ret *= (pow - (pow / i));
  }
  if (x != 1) ret *= (x - 1);
  return ret;
}
vector<long long> v[105];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  for (long long i = 1; i < m + 1; ++i) {
    int a, b;
    cin >> a >> b;
    v[a].push_back(i);
    v[b].push_back(i);
  }
  int c = m + 1;
  for (long long i = 1; i < n + 1; ++i) {
    if ((long long)v[i].size() == 0) {
      cout << "1\n";
      cout << i << " " << c << '\n';
      c++;
    } else {
      cout << (long long)v[i].size() << '\n';
      for (int j : v[i]) {
        cout << i << " " << j << '\n';
      }
    }
  }
  cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
  return 0;
}
