#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>

template <uint32_t Modulus>
class modular {
public:
  using value_type = uint32_t;
  using max_type = uint64_t;

  static constexpr value_type mod = Modulus;
  static constexpr value_type get_mod() { return mod; }
  static_assert(mod >= 2, "invalid mod :: smaller than 2");
  static_assert(mod < (value_type(1) << 31), "invalid mod :: over 2^31");

  template <class T>
  static constexpr value_type normalize(T value_) {
    if (value_ < 0) {
      value_ = -value_;
      value_ %= mod;
      if (value_ == 0) return 0;
      return mod - value_;
    }
    return value_ % mod;
  }

private:
  value_type value;

public:
  constexpr modular(): value(0) { }
  template <class T>
  explicit constexpr modular(T value_): value(normalize(value_)) { }
  template <class T>
  explicit constexpr operator T() { return static_cast<T>(value); }

  constexpr value_type get() const { return value; }
  constexpr modular operator - () const { return modular(mod - value); }
  constexpr modular operator ~ () const { return inverse(); }

  constexpr value_type &extract() { return value; }
  constexpr modular inverse() const { return power(mod - 2); }
  constexpr modular power(max_type exp) const {
    modular res(1), mult(*this);
    while (exp > 0) {
      if (exp & 1) res *= mult;
      mult *= mult;
      exp >>= 1;
    }
    return res;
  }

  constexpr modular operator + (const modular &rhs) const { return modular(*this) += rhs; }
  constexpr modular& operator += (const modular &rhs) { 
    if ((value += rhs.value) >= mod) value -= mod; 
    return *this; 
  }

  constexpr modular operator - (const modular &rhs) const { return modular(*this) -= rhs; }
  constexpr modular& operator -= (const modular &rhs) { 
    if ((value += mod - rhs.value) >= mod) value -= mod; 
    return *this; 
  }

  constexpr modular operator * (const modular &rhs) const { return modular(*this) *= rhs; }
  constexpr modular& operator *= (const modular &rhs) { 
    value = (max_type) value * rhs.value % mod;
    return *this;
  }

  constexpr modular operator / (const modular &rhs) const { return modular(*this) /= rhs; }
  constexpr modular& operator /= (const modular &rhs) { return (*this) *= rhs.inverse(); }

  constexpr bool zero() const { return value == 0; }
  constexpr bool operator == (const modular &rhs) const { return value == rhs.value; }
  constexpr bool operator != (const modular &rhs) const { return value != rhs.value; }
  friend std::ostream& operator << (std::ostream &stream, const modular &rhs) {
    return stream << rhs.value;
  }

};

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using m32 = modular<1000000007>;

size_t N;
std::vector<i32> graph[5000];
m32 dp[5000][5001][2];
m32 memo[5001][2];
m32 coeff[5001];
size_t size[5000];

void dfs(i32 u, i32 p) {
  size[u] = 1;
  dp[u][1][0] = m32(1);
  for (auto v: graph[u]) {
    if (v == p) {
      continue;
    }
    dfs(v, u);
    for (size_t i = 1; i <= size[u]; ++i) {
      for (size_t j = 1; j <= size[v]; ++j) {
        for (auto k: { 0, 1 }) {
          for (auto l: { 0, 1 }) {
            memo[i + j][k ^ l] += dp[u][i][k] * dp[v][j][l];
            memo[i][k ^ l ^ 1] += dp[u][i][k] * dp[v][j][l] * coeff[j];
          }
        }
      }
    }
    size[u] += size[v];
    for (size_t i = 1; i <= size[u]; ++i) {
      for (auto k: { 0, 1 }) {
        dp[u][i][k] = memo[i][k];
        memo[i][k] = m32();
      }
    }
  }
}

int main() {
  std::cin >> N;
  for ([[maybe_unused]] size_t i = 1; i < N; ++i) {
    i32 x, y;
    std::cin >> x >> y;
    --x; --y;
    graph[x].push_back(y);
    graph[y].push_back(x);
  }
  coeff[0] = m32(1);
  for (size_t i = 2; i <= N; i += 2) {
    coeff[i] = coeff[i - 2] * m32(i - 1);
  }
  dfs(0, -1);
  m32 ans;
  for (size_t i = 1; i <= N; ++i) {
    ans += dp[0][i][0] * coeff[i];
    ans -= dp[0][i][1] * coeff[i];
  }
  std::cout << ans << '\n';
  return 0;
}


Measured memory_bytes: 93148