import java.io.*; import java.util.*; public class Main_yukicoder827 { private static Scanner sc; private static Printer pr; private static void solve() { final int MOD = 1_000_000_007; int n = sc.nextInt(); List> edges = new ArrayList<>(n); for (int i = 0; i < n; i++) { edges.add(new ArrayList<>()); } for (int i = 0; i < n - 1; i++) { int u = sc.nextInt() - 1; int v = sc.nextInt() - 1; edges.get(u).add(v); edges.get(v).add(u); } int root = 0; int[] d = new int[n]; boolean[] used = new boolean[n]; used[root] = true; Deque st = new ArrayDeque<>(); st.push(root); while (!st.isEmpty()) { int e = st.pop(); for (int next : edges.get(e)) { if (used[next]) { continue; } d[next] = d[e] + 1; used[next] = true; st.push(next); } } PC pc = new PC(n, MOD); int[] cnt = new int[n]; for (int i = 0; i < n; i++) { cnt[d[i]]++; } // pr.println(Arrays.toString(d)); // pr.println(Arrays.toString(cnt)); long ans = 0; for (int i = 0; i < n; i++) { if (cnt[i] == 0) { continue; } // long tmp = 0; // for (int j = 1; j <= n; j++) { // tmp += pc.C(j - 1, i); // tmp %= MOD; // } long tmp = pc.C(n, i + 1); tmp *= pc.fact[i]; tmp %= MOD; tmp *= pc.fact[n - i - 1]; tmp %= MOD; tmp *= cnt[i]; tmp %= MOD; ans += tmp; ans %= MOD; } pr.println(ans); } /** * 組合せの数、順列、重複組み合わせなどを求める * MOD による剰余を返す */ static class PC { /** 除数。素数であることが基本的に必要(逆元をフェルマーの小定理で求めているため) */ int MOD; /** 階乗 {@code fact[i]=i! % MOD} */ long[] fact; /** 階乗の逆元 {@code ifact[i]=1/i! % MOD} */ long[] ifact; /** * size を引数の上限とし、MOD を除数として剰余を取るインスタンスを返す * O(size) の事前処理が必要 * * @param size 主なメソッドの引数の上限値 * @param MOD 除数 */ PC(int size, int MOD) { this.MOD = MOD; fact = new long[size + 1]; fact[0] = 1; for (int i = 1; i <= size; i++) { fact[i] = fact[i - 1] * i % MOD; } ifact = new long[size + 1]; int loop = MOD - 2; long x = fact[size]; ifact[size] = 1; while (loop > 0) { if (loop % 2 == 1) { ifact[size] = ifact[size] * x % MOD; } x = x * x % MOD; loop /= 2; } for (int i = size - 1; i >= 0; i--) { ifact[i] = ifact[i + 1] * (i + 1) % MOD; } } /** * 組合せの数 nCr を返す * O(1) * * @param n {@literal 0<=n<=size} * @param r {@literal r>=0} * @return nCr の値(MOD による剰余) */ int C(int n, int r) { if (r > n) { return 0; } return (int)(((fact[n] * ifact[n - r]) % MOD) * ifact[r] % MOD); } // /** * 順列 nPr を返す * O(1) * * @param n {@literal 0<=n<=size} * @param r {@literal r>=0} * @return nPr の値(MOD による剰余) */ int P(int n, int r) { if (r > n) { return 0; } return (int)((fact[n] * ifact[n -r]) % MOD); } /** * 重複組み合わせ nHr を返す * 異なるn種のものから重複を許してr個を選ぶ場合の数 * 0個の種類もあり得る * O(1) * * @param n {@literal 0<=n+r-1<=size}(他と上限が異なる) * @param r {@literal r>=0} * @return nHr の値(MOD による剰余) */ int H(int n, int r) { if (n == 0 && r == 0) { return 1; } return C(n + r - 1, r); } /** * 組合せの数 nCr を返す(nが大きいとき) * O(r) * * @param n {@literal n>=0}(上限はなくlongの範囲内であればよい) * @param r {@literal 0<=r<=size} * @return nCr の値(MOD による剰余) */ int C2(long n, int r) { long ret = ifact[r]; for (int i = 1; i <= r; i++) { long tmp = (n - r + i) % MOD; ret = (ret * tmp) % MOD; } return (int)ret; } /** * 第2種スターリング数 S(n,r) を返す * n人をちょうどr個のグループに分ける(グループの区別はなし) * グループの区別をする場合はr!S(n,r)。全射の場合の数と同義 * O(r log n) * * @param n {@literal n>=0}(上限はなくlongの範囲内であればよい) * @param r {@literal 0<=r<=size} * @return S(n,r) の値(MOD による剰余) */ int S(long n, int r) { //全射の場合の数を包除原理を使って求めて、1/r!をかける。 long ret = 0; for (int i = 1; i <= r; i++) { long tmp = (r - i) % 2 == 0 ? 1 : -1; tmp *= pow(i, n) * C(r, i) % MOD; ret = (ret + tmp + MOD) % MOD; } ret = ret * ifact[r] % MOD; return (int)ret; } /** * 繰り返し二乗法によるべき乗 {@code a^n % MOD} を返す * O(log n) * * @param a 底 * @param n べき指数 * @return a^n の値(MOD による剰余) */ long pow(int a, long n) { long loop = n; long ret = 1; long x = a; while (loop > 0) { if (loop % 2 == 1) { ret = ret * x % MOD; } x = x * x % MOD; loop /= 2; } return ret; } private final static int LIMIT = 66; private static int to; private static long[][] cache; /** * 組合せの数 nCr を返す(MODによる剰余なし) * パスカルの三角形によって求める * 限界:n=66 : 66C33=7_219_428_434_016_265_740 * O(n^2) * * @param n {@literal 0<=n<=66} * @param r {@literal 0<=r} * @return nCr の値 * @throws IllegalArgumentException {@literal n>66}の場合 */ static long CLong(int n, int r) { if (r > n) { return 0; } if (n > LIMIT) { throw new IllegalArgumentException(Integer.toString(n)); } if (cache == null) { cache = new long[LIMIT + 1][]; cache[0] = new long[1]; cache[0][0] = 1; to = 0; } if (cache[n] == null) { for (int i = to + 1; i <= n; i++) { cache[i] = new long[i + 1]; for (int j = 0; j <= i; j++) { if (j == 0 || j == i) { cache[i][j] = 1; } else { if (Long.MAX_VALUE - cache[i - 1][j - 1] < cache[i - 1][j]) { throw new IllegalArgumentException("Overflow"); } else { cache[i][j] = cache[i - 1][j - 1] + cache[i - 1][j]; } } } } to = n; } return cache[n][r]; } } // --------------------------------------------------- public static void main(String[] args) { sc = new Scanner(System.in); pr = new Printer(System.out); solve(); pr.close(); sc.close(); } static class Scanner { BufferedReader br; Scanner (InputStream in) { br = new BufferedReader(new InputStreamReader(in)); } private boolean isPrintable(int ch) { return ch >= '!' && ch <= '~'; } private boolean isCRLF(int ch) { return ch == '\n' || ch == '\r' || ch == -1; } private int nextPrintable() { try { int ch; while (!isPrintable(ch = br.read())) { if (ch == -1) { throw new NoSuchElementException(); } } return ch; } catch (IOException e) { throw new NoSuchElementException(); } } String next() { try { int ch = nextPrintable(); StringBuilder sb = new StringBuilder(); do { sb.appendCodePoint(ch); } while (isPrintable(ch = br.read())); return sb.toString(); } catch (IOException e) { throw new NoSuchElementException(); } } int nextInt() { try { // parseInt from Integer.parseInt() boolean negative = false; int res = 0; int limit = -Integer.MAX_VALUE; int radix = 10; int fc = nextPrintable(); if (fc < '0') { if (fc == '-') { negative = true; limit = Integer.MIN_VALUE; } else if (fc != '+') { throw new NumberFormatException(); } fc = br.read(); } int multmin = limit / radix; int ch = fc; do { int digit = ch - '0'; if (digit < 0 || digit >= radix) { throw new NumberFormatException(); } if (res < multmin) { throw new NumberFormatException(); } res *= radix; if (res < limit + digit) { throw new NumberFormatException(); } res -= digit; } while (isPrintable(ch = br.read())); return negative ? res : -res; } catch (IOException e) { throw new NoSuchElementException(); } } long nextLong() { try { // parseLong from Long.parseLong() boolean negative = false; long res = 0; long limit = -Long.MAX_VALUE; int radix = 10; int fc = nextPrintable(); if (fc < '0') { if (fc == '-') { negative = true; limit = Long.MIN_VALUE; } else if (fc != '+') { throw new NumberFormatException(); } fc = br.read(); } long multmin = limit / radix; int ch = fc; do { int digit = ch - '0'; if (digit < 0 || digit >= radix) { throw new NumberFormatException(); } if (res < multmin) { throw new NumberFormatException(); } res *= radix; if (res < limit + digit) { throw new NumberFormatException(); } res -= digit; } while (isPrintable(ch = br.read())); return negative ? res : -res; } catch (IOException e) { throw new NoSuchElementException(); } } float nextFloat() { return Float.parseFloat(next()); } double nextDouble() { return Double.parseDouble(next()); } String nextLine() { try { int ch; while (isCRLF(ch = br.read())) { if (ch == -1) { throw new NoSuchElementException(); } } StringBuilder sb = new StringBuilder(); do { sb.appendCodePoint(ch); } while (!isCRLF(ch = br.read())); return sb.toString(); } catch (IOException e) { throw new NoSuchElementException(); } } void close() { try { br.close(); } catch (IOException e) { // throw new NoSuchElementException(); } } } static class Printer extends PrintWriter { Printer(OutputStream out) { super(out); } } }