#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cout << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cout<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 200010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 29;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
///////////////////////////////////////////////////////////////////////////////////////////////////

ll fac[MAX_N], inv[MAX_N], fiv[MAX_N]; //fiv:inv(fac(i))

ll mod_pow(ll a, ll n) {
	if(n == 0) return 1;
	ll res = mod_pow(a, n / 2);
	if(n % 2 == 0) return res * res % mod;
	else return a * res % mod * res % mod;
}

ll invf(ll a) {
	return mod_pow(a, mod - 2);
}

void C_init(int n) {
	fac[0] = fac[1] = 1; inv[1] = 1;
	fiv[0] = fiv[1] = 1;
	rep(i, 2, n + 1) {
		fac[i] = fac[i - 1] * i % mod;
		inv[i] = mod - inv[mod % i] * (mod / i) % mod;
		fiv[i] = fiv[i - 1] * inv[i] % mod;
	}
}

ll C(int a, int b) { //assume a >= b
	if(a < b || a < 0 || b < 0) return 0;
	return fac[a] * fiv[b] % mod * fiv[a - b] % mod;
}

int N;
vector<int> G[MAX_N];

ll dp[5010][5010][2];
ll ep[5010][5010][2];
ll pow2inv[5010];

int loop(int v, int p) {
	int sz = 1;
	dp[v][1][0] = 1;
	rep(q, 0, sz(G[v])) {
		int n = G[v][q];
		if(p == n) continue;
		int ts = loop(n, v);
		rep(i, 0, sz + ts + 1) {
			rep(j, 0, 2) {
				ep[v][i][j] = 0;
			}
		}
		rep(i, 0, sz + 1) {
			rep(j, 0, ts + 1) {
				rep(k, 0, 2) {
					rep(l, 0, 2) {
						ADD(ep[v][i + j][(k + l) % 2], dp[v][i][k] * dp[n][j][l] % mod);
					}
				}
			}
		}
		
		rep(i, 0, sz + ts + 1) {
			rep(j, 0, 2) {
				dp[v][i][j] = ep[v][i][j];
			}
		}
		// rep(i, 0, sz + ts + 1) {
		// 	rep(j, 0, 2) {
		// 		debug(v, q, i, j, dp[v][i][j]);
		// 	}
		// }
		sz += ts;
	}
	for(int i = 0; i <= sz; i += 2) {
		rep(j, 0, 2) {
			ADD(dp[v][0][(j + 1) % 2], dp[v][i][j] * fac[i] % mod * pow2inv[i / 2] % mod * fiv[i / 2] % mod);
		}
	}
	// debug(v, vl(dp[v], dp[v] + sz + 1));
	// debug(v, sz);
	return sz;
}

void solve() {
	cin >> N;
	C_init(N);
	rep(i, 0, N - 1) {
		int a, b;
		cin >> a >> b; a--; b--;
		G[a].pb(b);
		G[b].pb(a);
	}
	pow2inv[0] = 1;
	rep(i, 0, N) {
		pow2inv[i + 1] = pow2inv[i] * inv[2] % mod;
	}
	loop(0, -1);
	// rep(i, 0, N) {
	// 	rep(j, 0, N + 1) {
	// 		rep(k, 0, 2) {
	// 			debug(i, j, k, dp[i][j][k]);
	// 		}
	// 	}
	// }
	cout << (dp[0][0][1] - dp[0][0][0] + mod) % mod << "\n";
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
	srand((unsigned int)time(NULL));
#ifdef LOCAL
	//freopen("in.txt", "wt", stdout); //for tester
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
#ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
	return 0;
}



Measured memory_bytes: 792576