#define _USE_MATH_DEFINES
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <utility>
#include <complex>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <limits>
#include <algorithm>
#include <array>
#include <random>
#include <complex>
#include <regex>
using namespace std;
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
typedef complex<ld> compd;
#define quickIO()	{cin.tie(0);	cout.sync_with_stdio(false);}
#define reach(i,a)	for(auto i:a)
#define rep(i,n)	for(int i=0;i<((int)n);i++)
#define REP(i,n)	for(int i=0;i<=((int)n);i++)
#define srep(i,a,n)	for(int i=a;i<((int)n);i++)
#define SREP(i,a,n)	for(int i=a;i<=((int)n);i++)
#define rrep(i,n)	for(int i=n-1;i>=0;i--)
#define RREP(i,n)	for(int i=n;i>=0;i--)
#define all(a)	(a).begin(),(a).end()
#define mp(a,b)	make_pair(a,b)
#define mt	make_tuple
#define pb	push_back
template<typename T> istream& operator >> (istream& is, vector<T>& vec) {
	for (T& x : vec)	is >> x;
	return is;
}
template<typename T> ostream& operator << (ostream& os, vector<T>& vec) {
	os << "[";
	rep(i, vec.size())	os << (i ? ", " : "") << vec[i];
	os << "]";
	return os;
}
template<typename T> istream& operator >> (istream& is, pair<T, T>& p) {
	is >> p.first >> p.second;
	return is;
}
template<typename T> ostream& operator << (ostream& os, pair<T, T>& p) {
	os << "(" << p.first << ", " << p.second << ")";
	return os;
}
int bitcnt(ll x) {
	x = ((x & 0xAAAAAAAAAAAAAAAA) >> 1) + (x & 0x5555555555555555);
	x = ((x & 0xCCCCCCCCCCCCCCCC) >> 2) + (x & 0x3333333333333333);
	x = ((x & 0xF0F0F0F0F0F0F0F0) >> 4) + (x & 0x0F0F0F0F0F0F0F0F);
	x = ((x & 0xFF00FF00FF00FF00) >> 8) + (x & 0x00FF00FF00FF00FF);
	x = ((x & 0xFFFF0000FFFF0000) >> 16) + (x & 0x0000FFFF0000FFFF);
	x = ((x & 0xFFFFFFFF00000000) >> 32) + (x & 0x00000000FFFFFFFF);
	return x;
}
int bitcnt(int x) {
	x = ((x & 0xAAAAAAAA) >> 1) + (x & 0x55555555);
	x = ((x & 0xCCCCCCCC) >> 2) + (x & 0x33333333);
	x = ((x & 0xF0F0F0F0) >> 4) + (x & 0x0F0F0F0F);
	x = ((x & 0xFF00FF00) >> 8) + (x & 0x00FF00FF);
	x = ((x & 0xFFFF0000) >> 16) + (x & 0x0000FFFF);
	return x;
}
ll sqrtll(ll x) {
	ll left = 0, right = x;
	rep(i, 100) {
		ll mid = (left + right) >> 1;
		if (mid*mid <= x)	left = mid;
		else	right = mid;
	}
	return left;
}
ll gcd(ll a, ll b) {
	return a % b == 0 ? b : gcd(b, a%b);
}
#define debug(x)	printf("Case #%d: ", x)
#define DEBUG 0
const ll inf = 1e18;
const ld infl = 1e100;
const ll mod = 1e9+7;
const ld eps = 1e-9;
const int dx[] = { 1,0,-1,0,0 };
const int dy[] = { 0,1,0,-1,0 };

ll dp[5010][5010][2];
ll dp2[5010][2];
ll cnt[5010];
vint edge[5000];
ll fact[5010];

void dfs(int cur, int parent) {
	dp[cur][1][0] = 1;
	cnt[cur] = 1;
	for (int to : edge[cur]) {
		if (to == parent)	continue;
		dfs(to, cur);
		SREP(i, 1, cnt[cur]) {
			SREP(j, 1, cnt[to]) {
				(dp2[i + j][0] += (dp[cur][i][0] * dp[to][j][0] % mod + dp[cur][i][1] * dp[to][j][1] % mod) % mod) %= mod;
				(dp2[i + j][1] += (dp[cur][i][0] * dp[to][j][1] % mod + dp[cur][i][1] * dp[to][j][0] % mod) % mod) %= mod;
				(dp2[i][1] += (dp[cur][i][0] * dp[to][j][0] % mod + dp[cur][i][1] * dp[to][j][1] % mod) % mod*fact[j] % mod) %= mod;
				(dp2[i][0] += (dp[cur][i][0] * dp[to][j][1] % mod + dp[cur][i][1] * dp[to][j][0] % mod) % mod*fact[j] % mod) %= mod;
			}
		}
		cnt[cur] += cnt[to];
		REP(i, cnt[cur]) {
			dp[cur][i][0] = dp2[i][0];
			dp[cur][i][1] = dp2[i][1];
			dp2[i][0] = dp2[i][1] = 0;
		}
	}
}

int main() {
	int n;	cin >> n;
	// 全通り数は(N-1)(N-3)(N-5)...3通り
	// そこからリボンが貼られていないものを引いていく。
	srep(i, 1, n) {
		int x, y;	cin >> x >> y;	x--;	y--;
		edge[x].push_back(y);
		edge[y].push_back(x);
	}
	fact[2] = 1;
	for (int i = 4; i <= 5000; i += 2) {
		fact[i] = (fact[i - 2] * (i - 1)) % mod;
	}
	dfs(0, -1);
	ll ret = 0;
	REP(i, cnt[0]) {
		(ret += (dp[0][i][0] - dp[0][i][1] + mod) * fact[i] % mod) %= mod;
	}
	// ret = (fact[n] - ret + mod) % mod;
	cout << ret << endl;
	return 0;
}

Measured memory_bytes: 391424