#include <bits/stdc++.h>
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(a) sort(a.begin(), a.end())
#define Reverse(a) reverse(a.begin(), a.end())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define Ans(f, y, n) if(f) cout << y << endl; else cout << n << endl;
#define int long long
#define INF 1000000000000000000
using namespace std;

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using PiP = pair<int, Pii>;
using PPi = pair<Pii, int>;
using bools = vector<bool>;

template<typename T>
void readv(vector<T> &a){ REP(i, a.size()) cin >> a[i]; }
void readi(vector<int> &a){ REP(i, a.size()){cin >> a[i]; a[i]--;} }
template<typename T>
void debug(vector<vector<T>> m){ REP(i, m.size()){ REP(j, m[i].size()){ cout << m[i][j] << ","; } cout << endl;} }

int mod = 1000000007;

struct edge{int to, cost;};

class Graph
{
public:
    int V;
    vector<vector<edge>> G;
    vector<mat> dp;

    Graph(int V): V(V){
        G = vector<vector<edge>>(V, vector<edge>(0));
        dp = vector<mat>(V);
    }

    void add_edge(int from, int to, int cost){
        G[from].push_back(edge({to, cost}));
    }

    void add_edge2(int v1, int v2, int cost){
        add_edge(v1, v2, cost);
        add_edge(v2, v1, cost);
    }

    void dfs(int v, int p, vec &C){

        int sz = G[v].size();
        if(p == -1) sz++;

        vector<mat> dp0 = vector<mat>(sz);
        dp0[0] = mat(1, vec(2));
        dp0[0][0] = vec({1, 0});
        int i0 = 0;
        REP(k, G[v].size()) if(G[v][k].to != p){
          int c = G[v][k].to;
          dfs(c, v, C);
          int n = dp0[i0].size(), m = dp[c].size();
          dp0[i0 + 1] = mat(n + m, vec(2, 0));
          //くっつける
          REP(i, n) REP(j, m){
            dp0[i0 + 1][i + j + 1][0] += dp0[i0][i][0] * dp[c][j][0] + dp0[i0][i][1] * dp[c][j][1];
            dp0[i0 + 1][i + j + 1][0] %= mod;
            dp0[i0 + 1][i + j + 1][1] += dp0[i0][i][0] * dp[c][j][1] + dp0[i0][i][1] * dp[c][j][0];
            dp0[i0 + 1][i + j + 1][1] %= mod;
          }
          //離す
          REP(i, n) REP(j, m) if(j % 2 == 1){
            dp0[i0 + 1][i][1] += ((dp0[i0][i][0] * dp[c][j][0] + dp0[i0][i][1] * dp[c][j][1]) % mod) * C[j + 1];
            dp0[i0 + 1][i][1] %= mod;
            dp0[i0 + 1][i][0] += ((dp0[i0][i][0] * dp[c][j][1] + dp0[i0][i][1] * dp[c][j][0]) % mod) * C[j + 1];
            dp0[i0 + 1][i][0] %= mod;
          }
          i0++;
        }
        dp[v] = dp0[sz - 1];
    }

    int getans(int s, vec &C){
      int ans = 0;
      REP(i, V) if(i % 2 == 1){
        ans += (dp[s][i][0] - dp[s][i][1]) * C[i + 1];
        ans = (ans % mod + mod) % mod;
      }
      return ans;
    }

};

int modpow(int x, int n, int m){
    int a = 1;
    IREP(i, 64){
        a = (a * a) % m;
        if(((n >> i) & 1) == 1) a = (a * x) % m;
    }
    return a;
}

class Combination
{
public:

    vec fact, invfact;
    int MAX_N, mod;

    Combination(int MAX_N, int mod): MAX_N(MAX_N), mod(mod) {
        initialize();
    }

    void initialize(){
        fact = vec(MAX_N + 1);
        invfact = vec(MAX_N + 1);
        fact[0] = 1;
        FOR(i, 1, MAX_N + 1){
            fact[i] = (fact[i - 1] * i) % mod;
        }
        invfact[MAX_N] = modpow(fact[MAX_N], mod - 2, mod);
        IREP(i, MAX_N){
            invfact[i] = (invfact[i + 1] * (i + 1)) % mod;
        }
    }

    int nCr(int n, int r){
        if(r > n || r < 0 || n < 0) return 0;
        if(n > MAX_N){
            MAX_N = n;
            initialize();
        }
        int a = fact[n];
        a = (a * invfact[r]) % mod;
        a = (a * invfact[n - r]) % mod;
        return a;
    }

    int nPr(int n, int r){
        if(r > n || r < 0 || n < 0) return 0;
        if(n > MAX_N){
            MAX_N = n;
            initialize();
        }
        int a = fact[n];
        a = (a * invfact[n - r]) % mod;
        return a;
    }
};

signed main(){

    int N; cin >> N;
    Graph T(N);
    vec x(N - 1), y(N - 1);
    REP(i, N - 1){
        cin >> x[i] >> y[i];
        T.add_edge2(x[i] - 1, y[i] - 1, 0);
    }

    Combination comb(N, mod);
    vec C(N + 1, 0);
    REP(i, N + 1){
      if(i % 2 == 0){
        int c = comb.fact[i] * modpow(modpow(2, i / 2, mod), mod - 2, mod);
        c %= mod;
        c *= modpow(comb.fact[i / 2], mod - 2, mod);
        C[i] = c % mod;
      }
    }
    //REP(i, N + 1) cout << C[i] << endl;
    T.dfs(0, -1, C);
    cout << T.getans(0, C) << endl;


    return 0;
}


Measured memory_bytes: 685184