#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
#include<cassert>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};

template<int mod>
struct ModInt {
    long long x;
 
    ModInt() : x(0) {}
    ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    explicit operator int() const {return x;}
 
    ModInt &operator+=(const ModInt &p) {
        if((x += p.x) >= mod) x -= mod;
        return *this;
    }
    ModInt &operator-=(const ModInt &p) {
        if((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }
    ModInt &operator*=(const ModInt &p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }
    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }
 
    ModInt operator-() const { return ModInt(-x); }
    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
 
    bool operator==(const ModInt &p) const { return x == p.x; }
    bool operator!=(const ModInt &p) const { return x != p.x; }
 
    ModInt inverse() const{
        int a = x, b = mod, u = 1, v = 0, t;
        while(b > 0) {
            t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        return ModInt(u);
    }

    ModInt power(long long p) const{
        int a = x;
        if (p==0) return 1;
        if (p==1) return ModInt(a);
        if (p%2==1) return (ModInt(a)*ModInt(a)).power(p/2)*ModInt(a);
        else return (ModInt(a)*ModInt(a)).power(p/2);
    }

    ModInt power(const ModInt p) const{
        return ((ModInt)x).power(p.x);
    }

    friend ostream &operator<<(ostream &os, const ModInt<mod> &p) {
        return os << p.x;
    }
    friend istream &operator>>(istream &is, ModInt<mod> &a) {
        long long x;
        is >> x;
        a = ModInt<mod>(x);
        return (is);
    }
};

using modint = ModInt<mod>;



int n;
vector<int> G[5010];
int siz[5010];
modint dp[5010][5010][2];//sdp[2][5010][2];
modint v[5010];

modint f(int x){
    if(x%2) return 0;
    return v[x/2];
}

void dfs(int s,int par){
    int i=0;
    vector<vector<vector<modint>>> sdp(2);
    siz[s]=1;
    sdp[i]=vector<vector<modint>>(siz[s]+1,vector<modint>(2,0));
    sdp[0][1][0]=1;
    for(int t:G[s]){
        if(t==par) continue;
        dfs(t,s);
        sdp[(i+1)%2]=vector<vector<modint>>(siz[s]+siz[t]+1,vector<modint>(2,0));
        rep(j1,siz[s]+1){
            rep(p1,2){
                rep(j2,siz[t]+1){
                    rep(p2,2){ 
                        sdp[(i+1)%2][j1+j2][(p1+p2)%2]+=sdp[i%2][j1][p1]*dp[t][j2][p2];
                        sdp[(i+1)%2][j1][(p1+p2+1)%2]+=f(j2)*sdp[i%2][j1][p1]*dp[t][j2][p2];
                    }
                }
            }
        }
        siz[s]+=siz[t];
        // rep(j,siz[s]+1){
        //     rep(p,2){
        //         cout << i+1 << ":" << j << " " << p << " " << dp[(i+1)%2][j][p] << endl; 
        //     }
        // }
        i+=1;
    }
    rep(j,siz[s]+1){
        rep(p,2){
            dp[s][j][p]=sdp[i%2][j][p];
        }
    }
    // rep(j,siz[s]+1){
    //     rep(p,2){
    //         cout << s << " " << j << " " << p << " " << dp[s][j][p] << endl;
    //     }
    // }
}

void solve(){
    cin >> n;
    v[0]=1;
    rep(i,n/2){
        v[i+1]=v[i]*(2*i+1);
    }
    v[0]=0;
    rep(i,n-1){
        int u,v;cin >> u >> v;u--;v--;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    dfs(0,-1);
    modint ans=0;
    rep(j,n-1){
        ans+=dp[0][j][1]*f(j)-dp[0][j][0]*f(j);
    }
    // rep(i,n){
    //     rep(j,siz[i]+1){
    //         rep(p,2){
    //             cout << i << " " << j << " " << p << " " << dp[i][j][p] << endl;
    //         }
    //     }
    // }
    cout << f(n)-ans << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(50);
    solve();
}

Measured memory_bytes: 397732