#include <iostream>
#include <vector>
#include <cstring>
using namespace std;

// 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) v += 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;
using mint = Fp<MOD>;
BiCoef<mint> bc;


int N;
vector<vector<int> > G;

// n 要素のマッチングの個数
vector<mint> pre;

// 木 DP
int size[5100];
mint dp[5100][5100][2];
mint sdp[5100][5100][2];

void rec(int v, int p = -1) {
    vector<int> chs;
    size[v] = 1;
    for (auto ch : G[v]) {
        if (ch == p) continue;
        rec(ch, v);
        chs.push_back(ch);
        size[v] += size[ch];
    }

    // サブ DP (初期化は i <= chs.size() で止めるのがポイント)
    for (int i = 0; i <= chs.size(); ++i)
        for (int j = 0; j <= size[v]; ++j)
            sdp[i][j][0] = sdp[i][j][1] = 0;
    sdp[0][0][0] = 1;
    int cur = 0;
    for (int i = 0; i < chs.size(); ++i) {
        int ch = chs[i];
        for (int num = 0; num <= cur; ++num) {
            for (int par = 0; par <= 1; ++par) {
                for (int num2 = 0; num2 <= size[ch]; ++num2) {
                    for (int par2 = 0; par2 <= 1; ++par2) {
                        // 切る
                        sdp[i+1][num][(par+par2+1)%2] += sdp[i][num][par] * dp[ch][num2][par2] * pre[num2];

                        // 切らない
                        sdp[i+1][num+num2][(par+par2)%2] += sdp[i][num][par] * dp[ch][num2][par2];
                    }
                }
            }
        }
        cur += size[ch];
    }

    // まとめ
    for (int num = 0; num <= size[v]; ++num) {
        for (int par = 0; par <= 1; ++par) {
            dp[v][num+1][par] = sdp[chs.size()][num][par];
        }
    }
}

int main() {
    bc.init(5100);

    // 入力
    cin >> N;
    G.assign(N, vector<int>());
    for (int i = 0; i < N-1; ++i) {
        int a, b; cin >> a >> b; --a, --b;
        G[a].push_back(b);
        G[b].push_back(a);
    }

    // 前処理
    pre.assign(N+1, 0);
    for (int n = 0; n <= N; n += 2) {
        pre[n] = bc.fact(n) * bc.finv(n/2) / modpow(mint(2), n/2);
    }

    // 木 DP
    memset(dp, 0, sizeof(dp));
    rec(0);

    // 集計
    mint res = 0;
    for (int num = 0; num <= N; ++num) {
        res += dp[0][num][0] * pre[num];
        res -= dp[0][num][1] * pre[num];
    }
    cout << res << endl;
}


Measured memory_bytes: 807424