# include <iostream>
# include <algorithm>
#include <array>
# include <cassert>
#include <cctype>
#include <climits>
#include <numeric>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <tuple>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <bitset>
# include <complex>
# include <chrono>
# include <random>
# include <limits.h>
# include <unordered_map>
# include <unordered_set>
# include <deque>
# include <cstdio>
# include <cstring>
#include <stdio.h>
#include<time.h>
#include <stdlib.h>
#include <cstdint>
#include <cfenv>
#include<fstream>
//#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
long long MOD = 1000000000 + 7;// ;//1000000000 + 7 998244353 924844033 1000000000 + 9;
constexpr long long INF = numeric_limits<LL>::max();
constexpr long long DINF = 1000000000000;
const double PI = acos(-1);
#define fir first
#define sec second
#define thi third
#define debug(x) cerr<<#x<<": "<<x<<'\n'
typedef pair<LL, LL> Pll;
typedef pair<double, double> Dll;
typedef pair<LL, pair<LL, LL>> Ppll;
typedef pair<LL, pair<LL, bitset<100001>>> Pbll;
typedef pair<LL, pair<LL, vector<LL>>> Pvll;
typedef pair<LL, LL> Vec2;
struct Tll { LL first, second, third; };
struct Fll { LL first, second, third, fourth; };
typedef pair<LL, Tll> Ptll;
#define rep(i,rept) for(LL i=0;i<rept;i++)
#define Rrep(i,mf) for(LL i=mf-1;i>=0;i--)
void YN(bool f) {
	if (f)
		cout << "YES" << endl;
	else
		cout << "NO" << endl;
}
void yn(bool f) {
	if (f)
		cout << "Yes" << endl;
	else
		cout << "No" << endl;
}
struct Edge { LL to, cost; };
struct edge {
	LL from, to, cost;
};
vector<vector<LL>>g;
vector<edge>ed;
vector<Pll>pv;
map<string, LL>ma;
set<LL>st;
int di[4][2] = { { 0,1 },{ 1,0 },{ 0,-1 },{ -1,0 } };
LL n, m, k, p, q, w, h, ans, cnt, sum, sub[5100], fact[5100], a[210000], b[210000]; 
vector<LL>dp[2][5100];
string str;
bool f;
char c[1100][1100];
void dfs(LL cur, LL par) {
	sub[cur]++;
	dp[0][cur].push_back(0);
	dp[1][cur].push_back(0);
	dp[0][cur].push_back(1);
	dp[1][cur].push_back(0);
	rep(x, g[cur].size()) {
		LL v = g[cur][x];
		if (v == par)continue;
		dfs(v, cur);
		vector<LL>table[2];
		table[0].resize(sub[cur] + sub[v]+1, 0);
		table[1].resize(sub[cur] + sub[v]+1, 0);
		for (LL i = 1; i <= sub[cur]; i++) {
			for (LL j = 1; j <= sub[v]; j++) {
				table[0][i + j] += (dp[0][v][j] * dp[0][cur][i] + dp[1][v][j] * dp[1][cur][i] );
				table[1][i + j] += (dp[0][v][j] * dp[1][cur][i]  + dp[1][v][j] * dp[0][cur][i] );
				table[0][i] += ((((dp[0][v][j] * fact[j]) % MOD)*dp[1][cur][i])
					+ (((dp[1][v][j] * fact[j]) % MOD)*dp[0][cur][i]));
				table[1][i] += ((((dp[0][v][j] * fact[j]) % MOD)*dp[0][cur][i])
					+ (((dp[1][v][j] * fact[j]) % MOD)*dp[1][cur][i]));
				table[0][i + j] %= MOD;
				table[1][i + j] %= MOD;
				table[0][i] %= MOD;
				table[1][i] %= MOD;
			}
		}
		swap(table[0], dp[0][cur]);
		swap(table[1], dp[1][cur]);
		sub[cur] += sub[v];
	}
}
int main() {
	cin >> n;
	g.resize(n);
	fact[2] = 1;
	for (int i = 2; i <= n + 1; i++) {
		if (i % 2 == 0)
			fact[i + 2] = (fact[i] * (i + 1)) % MOD;
	}
	rep(i, n-1) {
		LL x, y;
		cin >> x >> y;
		x--, y--;
		g[x].push_back(y);
		g[y].push_back(x);
	}
	dfs(0,-1);
	for (LL i = 1; i <= n;i++) {
		ans += ((dp[0][0][i]-dp[1][0][i]+MOD)%MOD)*fact[i]%MOD;
		ans %= MOD;
	}
	cout << ans << endl;
	return 0;
}


Measured memory_bytes: 138624