#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define sar(a,n) cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl

using namespace std;

template<typename S,typename T>auto&operator<<(ostream&o,pair<S,T>p){return o<<"{"<<p.fi<<","<<p.se<<"}";}
template<typename T>auto&operator<<(ostream&o,set<T>s){for(auto&e:s)o<<e<<" ";return o;}
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,priority_queue<S,T,U>q){while(!q.empty())o<<q.top()<<" ",q.pop();return o;}
template<typename K,typename T>auto&operator<<(ostream&o,map<K,T>m){for(auto&e:m)o<<e<<" ";return o;}
template<typename T>auto&operator<<(ostream&o,vector<T>v){for(auto&e:v)o<<e<<" ";return o;}
void ashow(){cout<<endl;}template<typename T,typename...A>void ashow(T t,A...a){cout<<t<<" ";ashow(a...);}

typedef pair<int,int> P;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<P> vp;
typedef vector<double> vd;
typedef vector<string> vs;

const int MAX_N = 5005;

vector<int> G[MAX_N];
int mult[MAX_N];

inline int add(int x,int y)
{
    return (x+y)%MOD;
}

inline int sub(int x,int y)
{
    return (x+MOD-y)%MOD;
}

inline int mul(int x,int y)
{
    return (ll)x*y%MOD;
}

// 最上位の連結成分内の頂点数, 条件を満たさないものの偶奇
vvi dfs(int u, int p)
{
    vvi dp1(2, vi(2, 0));
    auto& dp = dp1;
    dp[1][0] = 1;
    each(v,G[u]){
        if(v != p){
            auto res = dfs(v, u);
            vvi ndp(len(dp)+len(res)-1, vi(2, 0));
            srep(j,1,len(dp)){
                srep(k,1,len(res)){
                    // つなげる
                    rep(l,2){
                        rep(m,2){
                            ndp[j+k][l^m] = add(ndp[j+k][l^m], mul(dp[j][l], res[k][m]));
                        }
                    }
                    if(k % 2) continue;
                    // つなげない
                    rep(l,2){
                        rep(m,2){
                            ndp[j][!(l^m)] = add(ndp[j][!(l^m)], mul(dp[j][l], mul(res[k][m], mult[k])));
                        }
                    }
                }
            }
            dp = ndp;
        }
    }
    return dp;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    rep(i,n-1){
        int u,v;
        cin >> u >> v;
        G[u-1].pb(v-1), G[v-1].pb(u-1);
    }
    mult[2] = 1;
    for(int i = 3; i < n; i += 2){
        mult[i+1] = mul(mult[i-1], i);
    }
    auto res = dfs(0,-1);
    int ans = 0;
    srep(i,1,n+1){
        if(i % 2 == 0) ans = add(ans, mul(mult[i], sub(res[i][0], res[i][1])));
    }
    cout << ans << "\n";
    return 0;
}


Measured memory_bytes: 2480