/**
 *    author:  otera    
**/
#include<iostream>
#include<string> 
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm> 
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
using namespace std;

//#define int long long
typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const int inf=1e9+7;
const ll INF=1LL<<60 ;
const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

// modint: mod 計算を int を扱うように扱える構造体
template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator >> (istream &is, Fp<MOD>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

// 二項係数ライブラリ
template<class T> struct BiCoef {
    vector<T> fact_, inv_, finv_;
    constexpr BiCoef() {}
    constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
        int MOD = fact_[0].getmod();
        for(int i = 2; i < n; i++){
            fact_[i] = fact_[i-1] * i;
            inv_[i] = -inv_[MOD%i] * (MOD/i);
            finv_[i] = finv_[i-1] * inv_[i];
        }
    }
    constexpr T com(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n-k];
    }
    constexpr T fact(int n) const noexcept {
        if (n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if (n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if (n < 0) return 0;
        return finv_[n];
    }
};

const int MOD = 1000000007;
//const int MOD = 998244353;
using mint = Fp<MOD>;
BiCoef<mint> bc;

int n;
vector<vector<int>> g;

vector<mint> pre;

int num[5050];
mint dp[5050][5050][2];
mint sdp[5050][5050][2];

void dfs(int v, int p) {
    num[v] = 1;
    vector<int> chs;
    for(int nv: g[v]) {
        if(nv == p) continue;
        dfs(nv, v);
        chs.push_back(nv);
        num[v] += num[nv];
    }
    rep(i, (int)chs.size() + 1) {
        for(int j = 0; j <= num[v]; ++ j) {
            rep(k, 2) {
                sdp[i][j][k] = 0;
            }
        }
    }
    sdp[0][0][0] = 1;
    int curnum = 0;
    for(int i = 0; i < (int)chs.size(); ++ i) {
        for(int a = 0; a <= curnum; ++ a) {
            rep(b, 2) {
                for(int c = 0; c <= num[chs[i]]; ++ c) {
                    rep(d, 2) {
                        //切る
                        sdp[i + 1][a][(b + d + 1) % 2] += sdp[i][a][b] * dp[chs[i]][c][d] * pre[c];
                        //切らない
                        sdp[i + 1][a + c][(b + d) % 2] += sdp[i][a][b] * dp[chs[i]][c][d];
                    }
                }
            }
        }
        curnum += num[chs[i]];
    }
    for(int j = 0; j <= num[v]; ++ j) {
        rep(k, 2) {
            dp[v][j + 1][k] = sdp[(int)chs.size()][j][k];
        }
    }
}

void solve() {
	cin >> n;
    g.assign(n, vector<int>());
    rep(i, n - 1) {
        int x, y; cin >> x >> y; 
        -- x, -- y;
        g[x].pb(y);
        g[y].pb(x);
    }
    bc.init(5100);
    pre.assign(n + 1, 0);
    for(int i = 0; i <= n; i += 2) {
        pre[i] = 1;
        for(int j = 2; j <= i; j += 2) {
            pre[i] *= bc.com(j, 2);
        }
        pre[i] = pre[i] / bc.fact(i / 2);
    }
    rep(i, 5050) {
        rep(j, 5050) {
            rep(k, 2) {
                dp[i][j][k] = 0;
            }
        }
    }
    dfs(0, -1);
    mint ans = 0;
    for(int j = 2; j <= n; j += 2) {
        ans += dp[0][j][0] * pre[j];
        ans -= dp[0][j][1] * pre[j];
    }
    cout << ans << endl;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//int t; cin >> t; rep(i, t)solve();
	solve();
    return 0;
}

Measured memory_bytes: 795776