#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define Foxyy cin.tie(0); cout.sync_with_stdio(0); cout.tie(0);
struct Solver {
int& n;
vector<vector<int>>& adj;
void solve() {
if (n == 1) {
cout << "1\n";
cout << "0 1\n";
return;
}
vector<int> tree(n+1);
tree[0] = 0;
queue<pair<int, int>> q;
for (int i : adj[0]) {
q.push({i, 0});
}
int cnt = 0;
while (not q.empty()) {
auto [u, p] = q.front();
q.pop();
tree[u] = tree[p] ^ (1 << cnt);
// cerr << u << ' ' << p << ' ' << tree[u] << ' ' << tree[p] << '\n';
cnt++;
for (int v : adj[u]) if (v != p) {
q.push({v, u});
}
}
vector<int> masks(n-1);
for (int i = 0; i < n-1; i++) {
masks[i] = (3 << i);
}
cout << (1 << (n-1)) << '\n';
for (int i = 0; i < (1 << (n-1)); i++) {
int mask = 0;
for (int j = 0; j < n-1; j++) {
if ((i >> j) & 1) {
mask ^= masks[j];
}
}
for (auto x : tree) {
cout << (x ^ mask) << ' ';
}
cout << '\n';
}
}
};
signed main() {
Foxyy
int T = 1;
// cin >> T;
while(T--) {
int n;
cin >> n;
vector<vector<int>> adj(n+1);
for (int i = 0; i < n; i++) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
Solver solver{n, adj};
solver.solve();
}
}
