#include <cassert>
#include <algorithm>
#include <array>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <chrono>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>
#include <random>
#include <memory>
#include <utility>
#include <limits>
#include "limits.h"
 
#define rep(i, a, b) for (long long (i) = (a); (i) < (b); (i)++)
#define all(i) i.begin(), i.end()
#define debug(...) std::cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

void debug_out(){std::cerr<<std::endl;}

template<typename Head,typename... Tail>
void debug_out(Head h,Tail... t){
  std::cerr<<" "<<h;
  debug_out(t...);
}
 
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, std::pair<T1, T2> pa) {
  return os << pa.first << " " << pa.second;
}
 
template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T> vec) {
  for (int i = 0; i < vec.size(); i++)os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
 
template<typename T1,typename T2>
inline bool chmax(T1& a,T2 b){return a<b && (a=b,true);}
 
template<typename T1,typename T2>
inline bool chmin(T1& a,T2 b){return a>b && (a=b,true);}
 
long long pow_mod(long long a, long long b, long long mod=-1) {
  if(b==0)return 1;
  if ((a == 0)||(mod!=-1&&(a+mod)%mod==0)) {
    return 0;
  }
  long long x = 1;
  while (b > 0) {
    if (b & 1) {
      x = (mod!=-1)?(x * a) % mod:x*a;
    }
    a = (mod!=-1)?(a * a) % mod:a*a;
    b >>= 1;
  }
  return x;
}

// const long long MOD = 998244353;
const long long MOD = 1e9 + 7;

template <std::uint_fast64_t Modulus> class modint {
  using u64 = std::uint_fast64_t;

public:
  u64 a;

  constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
  constexpr u64 &value() noexcept { return a; }
  constexpr const u64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    u64 exp = Modulus - 2;
    while (exp) {
      if (exp % 2) {
        *this *= rhs;
      }
      rhs *= rhs;
      exp /= 2;
    }
    return *this;
  }
};

using ll = long long;
using P=std::pair<long long,long long>;

using mint=modint<MOD>;

mint dp[5010][5010][2];
mint per[5010];

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

  per[2]=1;
  for(ll i=4;i<5050;i+=2)per[i]=per[i-2]*(i-1);

  ll n;
  std::cin>>n;

  std::vector<std::vector<ll>> graph(n);
  std::vector<ll> size(n);

  rep(i,0,n-1){
    ll a,b;
    std::cin>>a>>b;
    a--;b--;
    graph[a].push_back(b);
    graph[b].push_back(a);
  }

  auto dfs=[&](auto f,ll now,ll par)->void{
    size[now]=1;
    dp[now][1][0]=1;
    dp[now][1][1]=0;
    for(ll to:graph[now]){
      if(to!=par){
        f(f,to,now);
        std::vector<std::vector<mint>> temp(size[now]+size[to]+1,std::vector<mint>(2,0));
        for(ll i=1;i<=size[now];i++){
          for(ll j=1;j<=size[to];j++){
            temp[i+j][0]+=dp[now][i][0]*dp[to][j][0]+dp[now][i][1]*dp[to][j][1];
            temp[i+j][1]+=dp[now][i][1]*dp[to][j][0]+dp[now][i][0]*dp[to][j][1];
            temp[i][0]+=per[j]*(dp[now][i][1]*dp[to][j][0]+dp[now][i][0]*dp[to][j][1]);
            temp[i][1]+=per[j]*(dp[now][i][0]*dp[to][j][0]+dp[now][i][1]*dp[to][j][1]);
          }
        }
        for(ll i=1;i<=size[now]+size[to];i++){
          dp[now][i][0]=temp[i][0];
          dp[now][i][1]=temp[i][1];
        }
        size[now]+=size[to];
      }
    }
  };

  ll root=0;
  dfs(dfs,root,-1);

  mint ans=0;
  for(ll i=1;i<=n;i++){
    ans+=per[i]*dp[root][i][0];
    ans-=per[i]*dp[root][i][1];
  }

  std::cout<<ans.value()<<"\n";

  return 0;
}


Measured memory_bytes: 391776