/*
_____
.'     '.
/  0   0  \
|     ^     |
|  \     /  |
\  '---'  /
'._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

struct chash
{
	int operator()(int x) const
	{
		x ^= (x >> 20) ^ (x >> 12);
		return x ^ (x >> 7) ^ (x >> 4);
	}
	int operator()(long long x) const
	{
		return x ^ (x >> 32);
	}
};

template<typename T> using orderedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;

template<class T>
void readi(T &x)
{
	T input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
	{
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = input * 10 + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	x = input;
}
template<class T>
void printi(T output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
template<class T, class U>
T normalize(T x, U mod = 1000000007)
{
	return (((x % mod) + mod) % mod);
}
long long randomizell(long long mod)
{
	return ((1ll << 45) * rand() + (1ll << 30) * rand() + (1ll << 15) * rand() + rand()) % mod;
}
int randomize(int mod)
{
	return ((1ll << 15) * rand() + rand()) % mod;
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 5013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;

int N;
vector<int> edge[MAXN];
int parent[MAXN], subtree[MAXN];
int dfact[MAXN];
vector<pii> dp[MAXN];
int ans;

void dfs(int u)
{
	subtree[u] = 1;
	for (int v : edge[u])
	{
		if (v == parent[u]) continue;
		parent[v] = u;
		dfs(v);
		subtree[u] += subtree[v];
	}
	return;
}
vector<pii> comb(vector<pii> a, vector<pii> b)
{
	// cerr << "help comb\n";
	// for (int i = 0; i < a.size(); i++)
	// {
	// 	cerr << a[i].fi << ' ' << a[i].se << endl;
	// }
	// cerr << "and comb\n";
	// for (int i = 0; i < b.size(); i++)
	// {
	// 	cerr << b[i].fi << ' ' << b[i].se << endl;
	// }
	vector<pii> res(a.size() + b.size() - 1);
	for (int i = 1; i < b.size(); i++)
	{
		for (int j = 1; j < a.size(); j++)
		{
			res[j].se += (1ll * dfact[i] % INF * b[i].fi % INF * a[j].fi % INF); if (res[j].se >= INF) res[j].se -= INF;
			res[j].fi += (1ll * dfact[i] % INF * b[i].fi % INF * a[j].se % INF); if (res[j].fi >= INF) res[j].fi -= INF;
			res[j].fi += (1ll * dfact[i] % INF * b[i].se % INF * a[j].fi % INF); if (res[j].fi >= INF) res[j].fi -= INF;
			res[j].se += (1ll * dfact[i] % INF * b[i].se % INF * a[j].se % INF); if (res[j].se >= INF) res[j].se -= INF;
			res[i + j].fi += (1ll * b[i].fi * a[j].fi % INF); if (res[i + j].fi >= INF) res[i + j].fi -= INF;
			res[i + j].se += (1ll * b[i].fi * a[j].se % INF); if (res[i + j].se >= INF) res[i + j].se -= INF;
			res[i + j].se += (1ll * b[i].se * a[j].fi % INF); if (res[i + j].se >= INF) res[i + j].se -= INF;
			res[i + j].fi += (1ll * b[i].se * a[j].se % INF); if (res[i + j].fi >= INF) res[i + j].fi -= INF;
		}
	}
	// cerr << "get res\n";
	// for (int i = 0; i < res.size(); i++)
	// {
	// 	cerr << res[i].fi << ' ' << res[i].se << endl;
	// }
	// cerr << "done\n";
	return res;
}
void solve(int u)
{
	for (int v : edge[u])
	{
		if (v == parent[u]) continue;
		parent[v] = u;
		solve(v);
	}
	//dp[u][x][flag] = in subtree of u, have x guys left over after flag deletions
	dp[u].PB({0, 0});
	dp[u].PB({1, 0});
	for (int v : edge[u])
	{
		if (v == parent[u]) continue;
		dp[u] = comb(dp[u], dp[v]);
		//delete this edge
	}
	return;
	//dp[u][flag][v] = u remove flagmod2 edges and get v guys left over
	//remove the edge from u to its parent
	//(-1)^F * f(F)
}
int32_t main()
{
	ios_base::sync_with_stdio(0);
	srand(time(0));
	// cout << fixed << setprecision(10);
	// cerr << fixed << setprecision(10);
	// if (fopen("input.in", "r"))
	// {
	// 	freopen ("input.in", "r", stdin);
	// 	freopen ("output.out", "w", stdout);
	// }
	cin >> N;
	if (N % 2)
	{
		cout << "0\n";
		return 0;
	}
	for (int i = 1; i < N; i++)
	{
		int u, v;
		cin >> u >> v;
		u--; v--;
		edge[u].PB(v);
		edge[v].PB(u);
	}
	parent[0] = N;
	dfs(0);
	dfact[0] = 1;
	dfact[1] = 0;
	for (int i = 2; i <= N + 2; i++)
	{
		dfact[i] = (1ll * dfact[i - 2] * (i - 1) % INF);
	}
	solve(0);
	for (int i = 1; i < dp[0].size(); i++)
	{
		ans += (1ll * dp[0][i].fi * dfact[i] % INF); if (ans >= INF) ans -= INF;
		ans -= (1ll * dp[0][i].se * dfact[i] % INF); if (ans < 0) ans += INF;
	}
	cout << ans << '\n';
	//you suck if for some vertex u, there's a 0 through it
	//there's two 0's -  there's three 0's + there's four 0's -  there's 5 0's + ...
	//either this guy doesnt suck, so # of guys
	// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}


Measured memory_bytes: 99072