import java.util.Arrays;

public class Main {

  private static void solve() {
    int n = ni();
    int[] from = new int[n - 1];
    int[] to = new int[n - 1];
    for (int i = 0; i < n - 1; i++) {
      from[i] = ni() - 1;
      to[i] = ni() - 1;
    }
    int mod = (int) 1e9 + 7;
    long[] f2 = new long[n + 1];
    f2[1] = 1;
    for (int i = 3; i <= n; i += 2) {
      f2[i] = f2[i - 2] * i % mod;
    }

    int[][] g = packU(n, from, to);
    long[][][] dp = new long[n][2][2];
    int[] num = new int[n];
    for (int i = 0; i < n; i++) {
      dp[i][0][1] = 1;
      num[i] = 1;
    }

    int[][] p3 = parents3(g, 0);
    int[] ord = p3[1];
    int[] par = p3[0];

    for (int k = n - 1; k >= 0; k--) {
      
      int now = ord[k];

      for (int next : g[now]) {
        if (next == par[now]) continue;
        long[][] ndp = new long[2][num[now] + num[next] + 1];
        for (int i = 1; i <= num[now]; i++) {
          for (int j = 1; j <= num[next]; j++) {
            ndp[0][i + j] += dp[next][0][j] * dp[now][0][i] % mod;
            ndp[0][i + j] += dp[next][1][j] * dp[now][1][i] % mod;
            ndp[1][i + j] += dp[next][0][j] * dp[now][1][i] % mod;
            ndp[1][i + j] += dp[next][1][j] * dp[now][0][i] % mod;
            ndp[0][i + j] %= mod;
            ndp[1][i + j] %= mod;
          }
          for (int j = 2; j <= num[next]; j += 2) {
            ndp[1][i] += dp[next][0][j] * dp[now][0][i] % mod * f2[j - 1] % mod;
            ndp[1][i] += dp[next][1][j] * dp[now][1][i] % mod * f2[j - 1] % mod;
            ndp[0][i] += dp[next][0][j] * dp[now][1][i] % mod * f2[j - 1] % mod;
            ndp[0][i] += dp[next][1][j] * dp[now][0][i] % mod * f2[j - 1] % mod;
            ndp[0][i] %= mod;
            ndp[1][i] %= mod;
          }
        }
        num[now] += num[next];
        dp[now] = ndp;
      }
    }

    long ret = 0;
    for (int i = 1; i <= n; i++) {
      ret += (dp[0][0][i] + mod - dp[0][1][i]) * f2[i - 1];
      ret %= mod;
    }
    System.out.println(ret);
  }

  public static int[][] parents3(int[][] g, int root) {
    int n = g.length;
    int[] par = new int[n];
    Arrays.fill(par, -1);

    int[] depth = new int[n];
    depth[0] = 0;

    int[] q = new int[n];
    q[0] = root;
    for (int p = 0, r = 1; p < r; p++) {
      int cur = q[p];
      for (int nex : g[cur]) {
        if (par[cur] != nex) {
          q[r++] = nex;
          par[nex] = cur;
          depth[nex] = depth[cur] + 1;
        }
      }
    }
    return new int[][] {par, q, depth};
  }


  static int[][] packU(int n, int[] from, int[] to) {
    int[][] g = new int[n][];
    int[] p = new int[n];
    for (int f : from)
      p[f]++;
    for (int t : to)
      p[t]++;
    for (int i = 0; i < n; i++)
      g[i] = new int[p[i]];
    for (int i = 0; i < from.length; i++) {
      g[from[i]][--p[from[i]]] = to[i];
      g[to[i]][--p[to[i]]] = from[i];
    }
    return g;
  }

  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}


Measured memory_bytes: 218832