#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
#include <climits>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
//typedef pair<ll, ll> P;
#define rep(i, n) for(ll i = 0; i < (n); i++)
#define revrep(i, n) for(ll i = (n)-1; i >= 0; i--)
#define pb push_back
#define f first
#define s second
#define chmin(x, y) x = min(x, y);
#define chmax(x, y) x = max(x, y);

//const ll INFL = LLONG_MAX;//10^18 = 2^60
const ll INFL = 1LL<<60;
//const int INF = INT_MAX;
const ll INF = 1 << 30;//10^9
ll MOD = 1000000007;
//ll MOD = 998244353;

vector<ll> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};

void pres(double A, ll x = 20){cout << fixed << setprecision(x) << A << endl;}
void BinarySay(ll x, ll y = 60){rep(i, y) cout << (x>>(y-1-i) & 1); cout << endl;}
ll cnt_bit(ll x){return __builtin_popcountll(x);}

ll pow_long(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2) res *= x;
    x *= x; k /= 2;
  }
  return res;
}

ll pow_mod(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2){
      res *= x; res %= MOD;
    }
    x *= x; x %= MOD;
    k /= 2;
  }
  return res;
}

ll inverse(ll x){return pow_mod(x, MOD - 2);};

ll gcd(ll a, ll b){
    if(b == 0) return a;
    return gcd(b, a % b);
}

ll lcm(ll x, ll y){
  ll res = x / gcd(x, y);
  res *= y;
  return res;
};

//コンビネーション
const int MAXcomb = 200010;
ll fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
//facはn!,finvは1/n!
//invは逆元
void COMinit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(int i = 2; i < MAXcomb; i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll comb(int n, int k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return 0;
    return fac[n] * finv[k] % MOD * finv[n-k] % MOD;
}

const int MAXkai = 200010;
ll kai_memo[MAXkai];
ll kai(ll N){
  if(kai_memo[N] != 0) return kai_memo[N];
  if(N <= 1) return 1;
  return kai_memo[N] = N * kai(N-1) % MOD;
}

ll N;
vector<ll> E[5010];
ll child[5010];
ll make_child(ll now, ll from){
  ll res = 1;
  for(ll to: E[now])if(to != from){
    res += make_child(to, now);
  }
  return child[now] = res;
}

ll dp[5010][5010][2];
ll tmp[5010][2];
ll Next[5010][2];
ll kaikai[5010];
void calc(ll now, ll from){
  for(ll to: E[now])if(to != from){
    calc(to, now);
  }
  rep(i, 5010)rep(j, 2){
    tmp[i][j] = 0;
    Next[i][j] = 0;
  }
  ll X = 1;
  tmp[1][0] = 1;//0: 偶数, 1: 奇数
  for(ll to: E[now])if(to != from){
    ll Y = child[to];
    rep(i, X+1)rep(j, Y+1){
      if(i == 0 || j == 0) continue;
      //くっつける
      Next[i+j][0] += tmp[i][0] * dp[to][j][0] % MOD + tmp[i][1] * dp[to][j][1] % MOD;
      Next[i+j][1] += tmp[i][0] * dp[to][j][1] % MOD + tmp[i][1] * dp[to][j][0] % MOD;
      Next[i+j][0] %= MOD;
      Next[i+j][1] %= MOD;

      //きる
      Next[i][0] += tmp[i][0] * dp[to][j][1] % MOD * kaikai[j] % MOD;
      Next[i][0] += tmp[i][1] * dp[to][j][0] % MOD * kaikai[j] % MOD;
      Next[i][0] %= MOD;

      Next[i][1] += tmp[i][0] * dp[to][j][0] % MOD * kaikai[j] % MOD;
      Next[i][1] += tmp[i][1] * dp[to][j][1] % MOD * kaikai[j] % MOD;
      Next[i][1] %= MOD;
    }
    X += Y;
    rep(i, X+1)rep(j, 2){
      tmp[i][j] = Next[i][j];
      Next[i][j] = 0;
    }
  }
  rep(i, 5010)rep(j, 2){
    dp[now][i][j] = tmp[i][j];
  }
}

void solve(){
  ll N;
  cin >> N;
  rep(i, N-1){
    ll a, b;
    cin >> a >> b;
    a--, b--;
    E[a].pb(b);
    E[b].pb(a);
  }
  kaikai[0] = 1;
  for(ll i = 2; i <= N; i++){
    kaikai[i] = kaikai[i-2] * (i - 1) % MOD;
  }
  make_child(0, -1);
  calc(0, -1);
  ll ans = 0;
  rep(i, 5010){
    ans += MOD - dp[0][i][1] * kaikai[i] % MOD + dp[0][i][0] * kaikai[i] % MOD;
    ans %= MOD;
  }
  cout << ans << endl;
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}


Measured memory_bytes: 394240