4
1 4
3 1
3 4
 5
4 1
4 3
5 3
2 4
 21
7 15
13 1
14 3
4 10
2 3
16 18
17 20
16 20
8 4
3 12
2 17
13 11
16 1
13 2
13 5
8 9
6 14
3 17
16 9
13 8
 3
3 1
3 2
 6
5 2
5 3
1 4
3 1
5 6
 60
17 34
46 22
50 44
46 33
41 21
31 33
48 6
38 19
35 60
2 24
49 29
7 53
34 1
19 55
32 1
31 42
27 28
4 53
6 50
21 34
1 10
12 36
54 8
16 13
51 43
45 51
54 20
13 53
34 33
49 33
51 11
59 34
15 5
59 28
30 39
13 30
58 4
34 14
3 9
19 34
4 18
26 48
56 54
3 43
57 25
3 41
35 3
48 44
19 13
54 1
23 31
59 47
5 1
46 40
6 26
20 25
37 5
17 24
20 52
 3
3 2
1 2
 39
6 13
15 39
10 35
31 28
4 21
12 39
3 7
3 13
6 1
5 14
36 28
12 15
18 38
30 29
19 34
36 16
20 22
8 13
38 32
26 39
21 37
1 7
15 27
12 26
8 3
6 14
29 2
25 23
32 21
5 16
32 25
6 8
13 10
23 30
34 37
29 33
28 14
36 5
 10
5 9
8 5
7 6
7 9
3 9
2 1
7 2
3 6
7 1

1
3 4 1 2  0
 3
13 2 1 7 3 17 1 19 13 8 1 21  0
 0
 2
48 44 1 6 6 26 1 12  0
 7
12 15 1 2 1 7 1 9 12 26 1 11 8 3 1 12 6 8 1 17 28 14 1 20 36 5 1 24  2
3 6 1 4 7 1 1 10 
#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
void checkpoint1() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
bool comp(pair<long long, long long> &a, pair<long long, long long> &b) {
  if (a.first != b.first)
    return a.first < b.first;
  else {
    if (a.second > b.second)
      return b.second < a.second;
    else if (a.second < b.second)
      return a.second < b.second;
  }
  return a.first > b.first;
}
long long powe(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) {
      res *= a;
      res %= 1000000007;
    }
    a *= a;
    a %= 1000000007;
    b >>= 1;
  }
  return res;
}
vector<long long> adj[1005];
bool vis[1005];
void dfs(long long v) {
  vis[v] = 1;
  for (auto u : adj[v]) {
    if (!vis[u]) dfs(u);
  }
}
void terminAtor() {
  long long n;
  cin >> n;
  pair<long long, long long> p[n + 1];
  for (long long i = 0; i < n - 1; i++) {
    long long x, y;
    cin >> x >> y;
    p[i + 1] = {x, y};
    adj[x].push_back(y);
    adj[y].push_back(x);
  }
  dfs(1);
  vector<long long> uc;
  for (long long i = 2; i <= n; i++) {
    if (!vis[i]) {
      uc.push_back(i);
      dfs(i);
    }
  }
  long long k = uc.size();
  if (k == 0) {
    cout << 0;
    return;
  }
  long long comp[n + 1], sz[n + 1];
  for (long long i = 0; i <= n; i++) {
    comp[i] = i;
    sz[i] = 1;
  }
  vector<pair<long long, long long> > store;
  for (long long i = 1; i <= n; i++) {
    long long x = p[i].first, y = p[i].second;
    long long a = x, b = y;
    while (a ^ comp[a]) a = comp[a];
    while (b ^ comp[b]) b = comp[b];
    if (a != b) {
      if (sz[a] < sz[b]) swap(a, b);
      sz[a] += sz[b];
      comp[b] = comp[x] = comp[y] = a;
    } else {
      store.push_back({x, y});
    }
  }
  auto it = store.begin();
  cout << k << "\n";
  for (long long i = 0; i < k; i++) {
    cout << "1 " << uc[i] << " " << it->first << " " << it->second << "\n";
    it++;
  }
  return;
}
int main() {
  checkpoint1();
  auto startrrr = high_resolution_clock::now();
  cout << setprecision(20);
  terminAtor();
  auto stoprrr = high_resolution_clock::now();
  auto duration = duration_cast<microseconds>(stoprrr - startrrr);
  return 0;
}
