#include <iostream>
#include <fstream>
#include <iomanip>
#include <climits>
#include <limits>
#include <algorithm>
#include <array>
#include <vector>
#include <deque>
#include <queue>
#include <list>
#include <stack>
#include <string>
#include <functional>
#include <numeric>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <unordered_map>
#include <random>
#include <cmath>
#include <complex>
// #include "utiltime.hpp"

using namespace std;

typedef long long int ll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;

const int INFL = (int)1e9;
const ll INFLL = (ll)1e18;
const double INFD = numeric_limits<double>::infinity();
const double PI = 3.14159265358979323846;
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#define Loopll(i, n) for(ll i = 0; i < (ll)n; i++)
#define Loop1(i, n) for(int i = 1; i <= (int)n; i++)
#define Loopll1(i, n) for(ll i = 1; i <= (ll)n; i++)
#define Loopr(i, n) for(int i = (int)n - 1; i >= 0; i--)
#define Looprll(i, n) for(ll i = (ll)n - 1; i >= 0; i--)
#define Loopr1(i, n) for(int i = (int)n; i >= 1; i--)
#define Looprll1(i, n) for(ll i = (ll)n; i >= 1; i--)
#define Loopitr(itr, container) for(auto itr = container.begin(); itr != container.end(); itr++)
#define printv(vector) Loop(i, vector.size()) { cout << vector[i] << " "; } cout << endl;
#define printmx(matrix) Loop(i, matrix.size()) { Loop(j, matrix[i].size()) { cout << matrix[i][j] << " "; } cout << endl; }
#define quickio() ios::sync_with_stdio(false); cin.tie(0);
#define bitmanip(m,val) static_cast<bitset<(int)m>>(val)
ll rndf(double x) { return (ll)(x + (x >= 0 ? 0.5 : -0.5)); }
ll floorsqrt(double x) { ll m = (ll)sqrt(x); return m + (m * m <= (ll)(x) ? 0 : -1); }
ll ceilsqrt(double x) { ll m = (ll)sqrt(x); return m + ((ll)x <= m * m ? 0 : 1); }
ll rnddiv(ll a, ll b) { return (a / b + (a % b * 2 >= b ? 1 : 0)); }
ll ceildiv(ll a, ll b) { return (a / b + (a % b == 0 ? 0 : 1)); }

/*******************************************************/

namespace mod_op {

	const ll MOD = (ll)1e9 + 7;

	class modll {
	private:
		ll val;
		inline ll modify(ll x) { ll ret = x % MOD; if (ret < 0) ret += MOD; return ret; }
		inline ll inv(ll x) {
			if (x == 0) return 1 / x;
			else if (x == 1) return 1;
			else return modify(inv(MOD % x) * modify(-MOD / x));
		}
	public:
		modll(ll init = 0) { val = modify(init); return; }
		modll(const modll& another) { val = another.val; return; }
		inline modll& operator=(const modll &another) { val = another.val; return *this; }
		inline modll operator+(const modll &x) { return (val + x.val) % MOD; }
		inline modll operator-(const modll &x) { return (val - x.val) % MOD; }
		inline modll operator*(const modll &x) { return (val * x.val) % MOD; }
		inline modll operator/(const modll &x) { return (val * inv(x.val)) % MOD; }
		inline modll& operator+=(const modll &x) { val = (val + x.val) % MOD; return *this; }
		inline modll& operator-=(const modll &x) { val = (val - x.val) % MOD; return *this; }
		inline modll& operator*=(const modll &x) { val = (val * x.val) % MOD; return *this; }
		inline modll& operator/=(const modll &x) { val = (val * inv(x.val)) % MOD; return *this; }
		inline bool operator==(const modll &x) { return val == x.val; }
		inline bool operator!=(const modll &x) { return val != x.val; }
		friend inline istream& operator >> (istream &is, modll& x) { is >> x.val; return is; }
		friend inline ostream& operator << (ostream &os, modll& x) { os << x.val; return os; }
		ll get_val() { return val; }
	};

	modll pow(modll n, ll p) {
		modll ret;
		if (p == 0) ret = 1;
		else if (p == 1) ret = n;
		else {
			ret = pow(n, p / 2);
			ret *= ret;
			if (p % 2 == 1) ret *= n;
		}
		return ret;
	}

	vector<modll> facts;

	inline void make_facts(int n) {
		if (facts.empty()) facts.push_back(modll(1));
		for (int i = facts.size(); i <= n; ++i) facts.push_back(modll(facts.back() * (ll)i));
		return;
	}

	vector<modll> ifacts;
	vector<modll> invs;

	inline void make_invs(int n) {
		if (invs.empty()) {
			invs.push_back(modll(0));
			invs.push_back(modll(1));
		}
		for (int i = invs.size(); i <= n; ++i) {
			// because 0 = MOD = kq + r, 1/k = -q/r
			invs.push_back(invs[(int)MOD % i] * ((int)MOD - (int)MOD / i));
		}
		return;
	}

	inline void make_ifacts(int n) {
		make_invs(n);
		if (ifacts.empty()) ifacts.push_back(modll(1));
		for (int i = ifacts.size(); i <= n; ++i) ifacts.push_back(modll(ifacts.back() * invs[i]));
		return;
	}

	//nCr
	modll combination(ll n, ll r) {
		if (n >= r && r >= 0) {
			modll ret;
			make_facts((int)n);
			make_ifacts((int)n);
			ret = facts[(unsigned)n] * ifacts[(unsigned)r] * ifacts[(unsigned)(n - r)];
			return ret;
		}
		else return 0;
	}

	modll get_fact(ll n) {
		make_facts((int)n);
		return facts[(int)n];
	}

	modll get_ifact(ll n) {
		make_ifacts((int)n);
		return ifacts[(int)n];
	}

	//log_a(b), if x does not exist, return -1
	ll disc_log(modll a, modll b) {
		ll ret = -1;
		ll m = ceilsqrt(MOD);
		unordered_map<ll, ll> mp;
		modll x = 1;
		Loop(i, m) {
			mp[x.get_val()] = i;
			x *= a;
		}
		x = modll(1) / pow(a, m);
		modll k = b;
		Loop(i, m) {
			if (mp.find(k.get_val()) == mp.end()) k *= x;
			else {
				ret = i * m + mp[k.get_val()];
				break;
			}
		}
		return ret;
	}
}

using namespace mod_op;
typedef vector<modll> vmodll;
typedef vector<vector<modll>> vvmodll;

typedef ll nodeval_t;
typedef ll edgeval_t;

struct tree_t {
	int n;           // |V|, index begins with 0
	vector<P> edges; // E
	vector<nodeval_t> vals; // value of nodes
	vector<edgeval_t> costs; // cost, distance, or weight of edges
};

class Tree {
private:
	struct node {
		int id; vi childs; int parent = -1;
		int deg = -1; // the number of edges of the path to the root
		int eid = -1; // edge id of the edge connected by its parent and itself
		int subtree_n = 1; // the number of nodes of the partial tree rooted by itself
		nodeval_t val; // value of the node itself
		edgeval_t cost; // cost of the edge connected by its parent and itself
		bool operator<(const node & another) const {
			return deg != another.deg ? deg < another.deg : id < another.id;
		}
	};
	struct edgeinfo {
		int eid; int to; edgeval_t cost;
	};
	int n;
	static const nodeval_t init_val = 0;
	static const edgeval_t init_cost = 1;
	vector<vector<edgeinfo>> edges;
	vvi sparse_ancestors;
	void tree_construction() {
		leaves = {};
		queue<int> que;
		que.push(root);
		while (que.size()) {
			int a = que.front(); que.pop();
			deg_order.push_back(a);
			if (a == Tree::root) nodes[a].deg = 0;
			int leaf_flag = true;
			Loop(i, edges[a].size()) {
				int b = edges[a][i].to;
				if (nodes[b].deg != -1) {
					nodes[a].parent = b;
					nodes[a].eid = edges[a][i].eid;
					nodes[a].cost = edges[a][i].cost;
					nodes[a].deg = nodes[b].deg + 1;
				}
				else {
					leaf_flag = false;
					nodes[a].childs.push_back(b);
					que.push(b);
				}
			}
			if (leaf_flag) leaves.push_back(a);
		}
		Loopr(i, n) {
			int a = deg_order[i];
			Loop(j, nodes[a].childs.size()) {
				int b = nodes[a].childs[j];
				nodes[a].subtree_n += nodes[b].subtree_n;
			}
		}
	}
public:
	vector<node> nodes;
	vi deg_order; // node ids, sorted by deg
	vi leaves;
	int root;
	// T should be non-empty tree
	Tree(tree_t T, int root = -1) {
		n = T.n;
		nodes.resize(n);
		Loop(i, n) {
			nodes[i].id = i;
			nodes[i].val = (int)(T.vals.size()) > i ? T.vals[i] : init_val;
			nodes[i].cost = init_cost;
		}
		edges.resize(n);
		Loop(i, n - 1) {
			edges[T.edges[i].first].push_back({ i, T.edges[i].second, ((int)(T.costs.size()) > i ? T.costs[i] : init_cost) });
			edges[T.edges[i].second].push_back({ i, T.edges[i].first, ((int)(T.costs.size()) > i ? T.costs[i] : init_cost) });
		}
		// the node which has the greatest degree will automatically decided as the root
		if (root < 0) {
			int max_d = -1;
			Loop(i, n) {
				if ((int)(edges[i].size()) > max_d) {
					Tree::root = i;
					max_d = edges[i].size();
				}
			}
		}
		else {
			this->root = min(root, n - 1);
		}
		tree_construction();
		return;
	}
	void solve() {
		vvmodll cnt(n, vmodll({ 0, 1 }));
		vmodll precalc(n + 1, 0);
		Loop1(i, n) {
			if (i % 2 == 0) precalc[i] = get_fact(i) * get_ifact(i / 2) / pow(modll(2), i / 2);
		}
		Loopr(i, n) {
			int a = deg_order[i];
			Loop(j, nodes[a].childs.size()) {
				int b = nodes[a].childs[j];
				vmodll buf = cnt[a];
				cnt[a] = vmodll(cnt[a].size() + cnt[b].size() - 1, 0);
				Loop(l, buf.size()) {
					Loop(k, cnt[b].size()) {
						cnt[a][l + k] += buf[l] * cnt[b][k];
					}
				}
			}
			Loop1(k, cnt[a].size() - 1) {
				if (k % 2 == 1) continue;
				cnt[a][0] -= cnt[a][k] * precalc[k];
			}
		}
		modll ans = modll(0) - cnt[root][0];
		cout << ans << endl;
	}
};

int main() {
	tree_t T;
	cin >> T.n;
	Loop(i, T.n - 1) {
		int s, t; cin >> s >> t;
		T.edges.push_back({ s - 1, t - 1 });
	}
	Tree tree(T, 0);
	tree.solve();
}


Measured memory_bytes: 70016