using System;
using System.Linq;
using System.Collections.Generic;
using System.Diagnostics;
using Debug = System.Diagnostics.Trace;
using SB = System.Text.StringBuilder;
using System.Numerics;
using static System.Math;
using Number = System.Int64;
namespace Program {
	public class Solver {
		Random rnd = new Random();
		public void Solve() {
			var n = ri;
			if (n == 1) {
				Console.WriteLine(0);
				return;
			}
			var K = ri;
			const int MK = 305;
			var dp = new long[MK, MK];
			var stop = new long[MK, MK];
			var ep = new long[MK];

			dp[0, 0] = 1;
			stop[0, 0] = 1;
			for (int k = 0; k < K; k++) {
				var next = new long[MK, MK];
				var mext = new long[MK, MK];
				for (int l = 0; l <= K; l++)
					for (int r = 0; r <= K; r++) {
						if (dp[l, r] == 0) continue;
						if (r < l) {
							add(ref next[l, r + 1], dp[l, r]);
							add(ref mext[l, r + 1], stop[l, r]);
						}
						add(ref next[l, r], dp[l, r] * (n - 2));
						add(ref mext[l, r], stop[l, r] * (n - 1));

						add(ref next[l + 1, r], dp[l, r]);
						add(ref mext[l + 1, r], dp[l, r]);
					}
				dp = next;
				stop = mext;
			}

			for (int i = 0; i <= K; i++)
				for (int r = 0; r <= K; r++) add(ref ep[r], dp[i, r]);


			var ans = 0L;
			for (int i = 1; i <= n; i++) {
				if (i <= K + 5) {
					for (int l = 0; l <= K; l++)
						for (int r = 0; r <= K; r++) {
							if (r >= i) continue;
							if (l > i - 1) continue;

							if (l == i - 1) {
								//Debug.WriteLine($"stop {i} {l} {r} {stop[l, r]}");
								add(ref ans, stop[i - 1, r] * (i - r));
							}
							else {
								//Debug.WriteLine($"go {i} {l} {r} {dp[l, r]}");
								add(ref ans, dp[l, r] * (i - r));
							}
						}
				}
				else {
					//Debug.WriteLine("po");
					for (int r = 0; r <= K; r++) {
						add(ref ans, ep[r] * (i - r));
					}
				}
			}
			Console.WriteLine(ans);
		}
		const long M = (long)1e9 + 7;
		void add(ref long u, long v) {
			u += v;
			u %= 1000000007;
		}
		const long INF = 1L << 60;
		static int[] dx = { -1, 0, 1, 0 };
		static int[] dy = { 0, 1, 0, -1 };
		int ri { get { return sc.Integer(); } }
		long rl { get { return sc.Long(); } }
		double rd { get { return sc.Double(); } }
		string rs { get { return sc.Scan(); } }
		public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());

		static T[] Enumerate<T>(int n, Func<int, T> f) {
			var a = new T[n];
			for (int i = 0; i < a.Length; ++i) a[i] = f(i);
			return a;
		}
		static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
	}
}

#region main
static class Ex {
	static public string AsString(this IEnumerable<char> ie) { return new string(ie.ToArray()); }
	static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") {
		return string.Join(st, ie);
	}
	static public void Main() {
		//Console.SetOut(new Program.IO.Printer(Console.OpenStandardOutput()) { AutoFlush = false });
		var solver = new Program.Solver();
		solver.Solve();
		Console.Out.Flush();
	}
}
#endregion
#region Ex
namespace Program.IO {
	using System.IO;
	using System.Text;
	using System.Globalization;

	public class Printer : StreamWriter {
		public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
		public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
	}

	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 != 0; b = (char)read()) if (b != '\r') sb.Append(b);
			return sb.ToString();
		}
		public long Long() { return isEof ? long.MinValue : long.Parse(Scan()); }
		public int Integer() { return isEof ? int.MinValue : int.Parse(Scan()); }
		public double Double() { return isEof ? double.NaN : double.Parse(Scan(), CultureInfo.InvariantCulture); }
	}
}

#endregion