#include <iostream>
#include <vector>
#include <functional>

template <class T>
std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }

template <int MOD>
struct ModInt {
    using lint = long long;
    int val;

    // constructor
    ModInt(lint v = 0) : val(v % MOD) {
        if (val < 0) val += MOD;
    };

    // unary operator
    ModInt operator+() const { return ModInt(val); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt inv() const { return this->pow(MOD - 2); }

    // arithmetic
    ModInt operator+(const ModInt& x) const { return ModInt(*this) += x; }
    ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; }
    ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; }
    ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; }
    ModInt pow(lint n) const {
        auto x = ModInt(1);
        auto b = *this;
        while (n > 0) {
            if (n & 1) x *= b;
            n >>= 1;
            b *= b;
        }
        return x;
    }

    // compound assignment
    ModInt& operator+=(const ModInt& x) {
        if ((val += x.val) >= MOD) val -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt& x) {
        if ((val -= x.val) < 0) val += MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt& x) {
        val = lint(val) * x.val % MOD;
        return *this;
    }
    ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); }

    // compare
    bool operator==(const ModInt& b) const { return val == b.val; }
    bool operator!=(const ModInt& b) const { return val != b.val; }

    // I/O
    friend std::istream& operator>>(std::istream& is, ModInt& x) noexcept { return is >> x.val; }
    friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; }
};

template <class Cost = int>
struct Edge {
    int src, dst;
    Cost cost;
    Edge(int src = -1, int dst = -1, Cost cost = 1)
        : src(src), dst(dst), cost(cost){};

    bool operator<(const Edge<Cost>& e) const { return this->cost < e.cost; }
    bool operator>(const Edge<Cost>& e) const { return this->cost > e.cost; }
};

template <class Cost = int>
using Graph = std::vector<std::vector<Edge<Cost>>>;

constexpr int MOD = 1e9 + 7;
using mint = ModInt<MOD>;

void solve() {
    int n;
    std::cin >> n;

    std::vector<mint> comb(n + 1, 1);
    for (int i = 1; i <= n; ++i) {
        comb[i] = (i % 2 == 1 ? 0 : comb[i - 2] * (i - 1));
    }

    Graph<> graph(n);
    for (int i = 0; i < n - 1; ++i) {
        int u, v;
        std::cin >> u >> v;
        --u, --v;
        graph[u].emplace_back(u, v);
        graph[v].emplace_back(v, u);
    }

    std::function<std::vector<std::vector<mint>>(int, int)>
        dfs = [&](int v, int p) -> std::vector<std::vector<mint>> {
        auto dp = vec(2, vec(2, mint(0)));
        dp[0][1] = 1;
        int sz = 1;

        for (auto e : graph[v]) {
            int u = e.dst;
            if (u == p) continue;

            auto cdp = dfs(u, v);
            int csz = cdp.front().size() - 1;

            auto ndp = vec(2, vec(sz + csz + 1, mint(0)));

            for (int i = 0; i < 2; ++i) {
                for (int j = 0; j < 2; ++j) {
                    for (int x = 0; x <= sz; ++x) {
                        for (int y = 0; y <= csz; ++y) {
                            ndp[(i + j) % 2][x + y] += dp[i][x] * cdp[j][y];
                        }
                    }
                }
            }

            sz += csz;
            std::swap(dp, ndp);
        }

        for (int i = 0; i < 2; ++i) {
            for (int x = 1; x <= sz; ++x) {
                dp[1 - i][0] += dp[i][x] * comb[x];
            }
        }

        return dp;
    };

    auto dp = dfs(0, -1);
    std::cout << dp[1][0] - dp[0][0] << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}


Measured memory_bytes: 1920