using System; using System.Linq; using System.Collections.Generic; using Debug = System.Diagnostics.Debug; using StringBuilder = System.Text.StringBuilder; using System.Numerics; //using System.Threading.Tasks; namespace Program { public class Solver { public void Solve() { var n = sc.Integer(); ModInteger ans = 0; var table = new ModCombinationTable(1000); var dp = new ModInteger[1000, 1000]; dp[0, 0] = 1; for (int i = 0; i < 999; i++) for (int j = 0; j < 999; j++) { dp[i + 1, j + 1] += dp[i, j]; dp[i + 1, j] += j * dp[i, j]; } for (int i = 1; i <= n; i++) { for (int j = i; j <= n; j++) { var C = table[n, j]; ans += C * dp[j, i] * ModInteger.Pow(i * (i - 1), n - j); } } IO.Printer.Out.WriteLine(ans); } public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput()); static T[] Enumerate(int n, Func f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; } static public void Swap(ref T a, ref T b) { var tmp = a; a = b; b = tmp; } } } #region main static class Ex { static public string AsString(this IEnumerable ie) { return new string(System.Linq.Enumerable.ToArray(ie)); } static public string AsJoinedString(this IEnumerable ie, string st = " ") { return string.Join(st, ie); } static public void Main() { var solver = new Program.Solver(); solver.Solve(); Program.IO.Printer.Out.Flush(); } } #endregion #region Ex namespace Program.IO { using System.IO; using System.Text; using System.Globalization; public class Printer : StreamWriter { static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; } public static Printer Out { get; set; } public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } } public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { } public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { } public void Write(string format, T[] source) { base.Write(format, source.OfType().ToArray()); } public void WriteLine(string format, T[] source) { base.WriteLine(format, source.OfType().ToArray()); } } public class StreamScanner { public StreamScanner(Stream stream) { str = stream; } public readonly Stream str; private readonly byte[] buf = new byte[1024]; private int len, ptr; public bool isEof = false; public bool IsEndOfStream { get { return isEof; } } private byte read() { if (isEof) return 0; if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } } return buf[ptr++]; } public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; } public string Scan() { var sb = new StringBuilder(); for (var b = Char(); b >= 33 && b <= 126; b = (char)read()) sb.Append(b); return sb.ToString(); } public string ScanLine() { var sb = new StringBuilder(); for (var b = Char(); b != '\n'; b = (char)read()) if (b == 0) break; else if (b != '\r') sb.Append(b); return sb.ToString(); } public long Long() { if (isEof) return long.MinValue; long ret = 0; byte b = 0; var ng = false; do b = read(); while (b != '-' && (b < '0' || '9' < b)); if (b == '-') { ng = true; b = read(); } for (; true; b = read()) { if (b < '0' || '9' < b) return ng ? -ret : ret; else ret = ret * 10 + b - '0'; } } public int Integer() { return (isEof) ? int.MinValue : (int)Long(); } public double Double() { return double.Parse(Scan(), CultureInfo.InvariantCulture); } private T[] enumerate(int n, Func f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(); return a; } public char[] Char(int n) { return enumerate(n, Char); } public string[] Scan(int n) { return enumerate(n, Scan); } public double[] Double(int n) { return enumerate(n, Double); } public int[] Integer(int n) { return enumerate(n, Integer); } public long[] Long(int n) { return enumerate(n, Long); } } } #endregion #region ModNumber public partial struct ModInteger { public const long Mod = (long)1e9 + 7; public long num; public ModInteger(long n) : this() { num = n % Mod; } public override string ToString() { return num.ToString(); } public static ModInteger operator +(ModInteger l, ModInteger r) { var n = l.num + r.num; if (n >= Mod)n -= Mod; return new ModInteger(n); } public static ModInteger operator -(ModInteger l, ModInteger r) { var n = l.num - r.num; if (n < 0)n += Mod; return new ModInteger(n); } public static ModInteger operator *(ModInteger l, ModInteger r) { return new ModInteger((l.num * r.num) % Mod); } public static implicit operator ModInteger(long n) { return new ModInteger(n); } } #endregion #region CombinationTable public class ModCombinationTable { ModInteger[][] nCr; public ModCombinationTable(int n) { nCr = new ModInteger[n + 1][]; for (int i = 0; i <= n; i++) nCr[i] = new ModInteger[i + 2]; nCr[0][0] = 1; for (int i = 0; i <= n; i++) { nCr[i][0] = 1; for (int j = 1; j <= i; j++) nCr[i][j] = nCr[i - 1][j - 1] + nCr[i - 1][j]; } } public ModInteger this[int n, int r] { get { if (n < 0 || n > nCr.Length) throw new IndexOutOfRangeException("n<=0 || n>N "); if (r < 0 || r > n) throw new IndexOutOfRangeException("r<=0 ||r>n"); return nCr[n][r]; } } public ModInteger RepeatedCombination(int n, int k) { if (k == 0) return 1; return this[n + k - 1, k]; } } #endregion #region ModPow public partial struct ModInteger { static public ModInteger Pow(ModInteger v, ModInteger k) { ModInteger ret = 1; var n = k.num; for (; n > 0; n >>= 1, v *= v) { if ((n & 1) == 1) ret = ret * v; } return ret; } } #endregion