#include <bits/stdc++.h>
 
using namespace std;
using ll = long long;
// #define int ll
using PII = pair<int, int>;
 
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
 
template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }
 
template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) { 
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }
 
template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
  out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
  for(T& x: vec) {is >> x;} return is;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
  out<<'['; for(T i: a) {out<<i<<',';} out<<']'; return out;
}
 
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const int MOD = 1000000007;

struct mint {
  ll x;
  mint(): x(0) { }
  mint(ll y) : x(y>=0 ? y%MOD : y%MOD+MOD) {}
  ll get() const { return x; }

  // e乗
  mint pow(ll e) {
    ll a = 1, p = x;
    while(e > 0) {
      if(e%2 == 0) {p = (p*p) % MOD; e /= 2;}
      else {a = (a*p) % MOD; e--;}
    }
    return mint(a);
  }

  // Comparators
  bool operator <(mint b) { return x < b.x; }
  bool operator >(mint b) { return x > b.x; }
  bool operator<=(mint b) { return x <= b.x; }
  bool operator>=(mint b) { return x >= b.x; }
  bool operator!=(mint b) { return x != b.x; }
  bool operator==(mint b) { return x == b.x; }

  // increment, decrement
  mint operator++() { x++; return *this; }
  mint operator++(signed) { return x++; }
  mint operator--() { x--; return *this; }
  mint operator--(signed) { return x--; }

  // Basic Operations
  mint &operator+=(mint that) {
    x += that.x;
    if(x >= MOD) x -= MOD;
    return *this;
  }
  mint &operator-=(mint that) {
    x -= that.x;
    if(x < 0) x += MOD;
    return *this;
  }
  mint &operator*=(mint that) {
    x = (ll)x * that.x % MOD;
    return *this;
  }
  mint &operator/=(mint that) {
    x = (ll)x * that.pow(MOD-2).x % MOD;
    return *this;
  }
  mint &operator%=(mint that) {
    x = (ll)x % that.x;
    return *this;
  }
  mint operator+(mint that)const{return mint(*this) += that;}
  mint operator-(mint that)const{return mint(*this) -= that;}
  mint operator*(mint that)const{return mint(*this) *= that;}
  mint operator/(mint that)const{return mint(*this) /= that;}
  mint operator%(mint that)const{return mint(*this) %= that;}
};
// Input/Output
ostream &operator<<(ostream& os, mint a) { return os << a.x; }
istream &operator>>(istream& is, mint &a) { return is >> a.x; }

signed main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n;
  cin >> n;
  vector<vector<ll>> g(n);
  REP(i, n-1) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    g[a].push_back(b);
    g[b].push_back(a);
  }

  vector<mint> c(n+1);
  c[2] = 1;
  for(ll i=4; i<=n; i+=2) {
    c[i] = c[i-2] * (i-1);
  }

  // 2乗の木DP
  function<vector<vector<mint>>(ll,ll)> dfs = [&](ll v, ll par) {
    auto ret = make_v<mint>(2,2);
    ret[1][0] = 1;
    for(auto to: g[v]) {
      if(to == par) continue;
      auto tmp = dfs(to, v);
      auto nret = make_v<mint>(ret.size()+tmp.size()-1, 2);
      REP(i, ret.size()) REP(j, tmp.size()) {
        // vからtoまでの辺を切断
        nret[i][0] += ret[i][0] * tmp[j][1] * c[j] + ret[i][1] * tmp[j][0] * c[j]; 
        nret[i][1] += ret[i][0] * tmp[j][0] * c[j] + ret[i][1] * tmp[j][1] * c[j];
        // vからtoまでの辺をつないだまま
        nret[i+j][0] += ret[i][0] * tmp[j][0] + ret[i][1] * tmp[j][1];
        nret[i+j][1] += ret[i][0] * tmp[j][1] + ret[i][1] * tmp[j][0];
      }
      swap(ret, nret);
    }
    return ret;
  };

  auto ret = dfs(0, -1);

  mint ans = 0;
  REP(i, ret.size()) {
    ans += ret[i][0] * c[i];
    ans -= ret[i][1] * c[i];
  }
  cout << ans << endl;

  return 0;
}


Measured memory_bytes: 2140