#include <bits/stdc++.h>
#define int long long
#define vi vector<int>
#define ii pair<int, int>
#define f first
#define s second
#define all(x) (x).begin(), (x).end()
#define P 31
#define mod 1'000'000'007
#define inf 1'000'000'000'000'000'000
#define pb push_back
#define str string
#define sz(x) (x).size()
#define vvi vector<vi>
#define fun function
#define oopt cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(false);
#define file freopen("problemname.in", "r", stdin); freopen("pr.out", "w", stdout);
#define dbg(v) cout << "Line(" << __LINE__ << ") -> " << #v << " = " << (v) << endl;
using namespace std;
template <class T, int SZ> using arr = array<T, SZ>;
vi graf[30];
void solve()
{
int n;
cin >> n;
for (int i = 0; i < n; i++)
{
int u, v;
cin >> u >> v;
graf[u].pb(v);
graf[v].pb(u);
}
cout << (1ll<<n-1) << "\n";
for (int i = 0; i < (1ll<<n); i++)
{
if (__builtin_popcountll(i)%2)
continue;
vi id(n+1, -1);
id[0]=i;
queue<int> q;
q.push(0);
int st=0;
while (!q.empty())
{
int u = q.front();
q.pop();
for (int v:graf[u])
{
if (id[v]==-1)
{
// cout << v << " " << id[u] << "\n";
id[v]=(id[u]^(1ll<<st));
st++;
q.push(v);
}
}
}
for (int v:id)
cout << v << " ";
cout << "\n";
}
}
signed main()
{
oopt;
int t = 1;
// cin >> t;
while (t--)
solve();
return 0;
}
