#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
using namespace std;
typedef long long LL;
typedef long double LD;
typedef complex<LD> CMP;
typedef int vert;
typedef vector< vector<vert> > graph;
class HatRack { public:
long long countWays(vector <int> knob1, vector <int> knob2)
{
int N = knob1.size() + 1;
graph G(N);
for(int i=0; i<knob1.size(); ++i) {
int u = knob1[i] - 1;
int v = knob2[i] - 1;
G[u].push_back(v);
G[v].push_back(u);
}
memo.assign((N+1)*N*N, -1);
LL total = 0;
for(int root=0; root<N; ++root)
total += solve(G, N, root);
return total;
}
LL solve(const graph& G, int N, vert root)
{
return rec(G, N, N, root, 1);
}
vector<LL> memo;
LL rec(const graph& G, const int N, int pre, int cur, int loc) {
int key = (pre*N+cur)*N+(loc-1);
if(memo[key] != -1)
return memo[key];
vector<int> e_child;
if(loc*2+0 <= N) e_child.push_back(loc*2+0);
if(loc*2+1 <= N) e_child.push_back(loc*2+1);
vector<int> r_child;
for(int i=0; i<G[cur].size(); ++i)
if(G[cur][i] != pre)
r_child.push_back(G[cur][i]);
if(e_child.size() != r_child.size())
return memo[key] = 0;
LL total = 0;
do {
LL me = 1;
for(int i=0; i<e_child.size(); ++i)
me *= rec(G, N, cur, r_child[i], e_child[i]);
total += me;
} while( next_permutation(e_child.begin(), e_child.end()) );
return memo[key] = total;
}
};
// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
{ ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
{ os << "{ ";
for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const long long& Expected, const long long& Received) {
bool ok = (Expected == Received);
if(ok) cerr << "PASSED" << timer() << endl; else { cerr << "FAILED" << timer() << endl;
cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END verify_case(_, HatRack().countWays(knob1, knob2));}
int main(){
CASE(0)
int knob1_[] = {1};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {2};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 2LL;
END
CASE(1)
int knob1_[] = {1,1};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {2,3};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 2LL;
END
CASE(2)
int knob1_[] = {1,1,1,1};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {2,3,4,5};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 0LL;
END
CASE(3)
int knob1_[] = {6,6,6,4,1};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {1,2,4,5,3};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 0LL;
END
CASE(4)
int knob1_[] = {1,1,2,2,11,11,8,8,3,3,4,4,5};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {2,3,11,8,12,13,9,10,4,5,7,6,14};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 16LL;
END
CASE(5)
int knob1_[] = {1,2,3,4,5,6,7,8,9};
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = {2,3,4,5,6,7,8,9,10};
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = 0LL;
END
/*
CASE(6)
int knob1_[] = ;
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = ;
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = LL;
END
CASE(7)
int knob1_[] = ;
vector <int> knob1(knob1_, knob1_+sizeof(knob1_)/sizeof(*knob1_));
int knob2_[] = ;
vector <int> knob2(knob2_, knob2_+sizeof(knob2_)/sizeof(*knob2_));
long long _ = LL;
END
*/
}
// END CUT HERE