Problem:
Score : 800 points

Problem Statement

There are N squares lining up in a row, numbered 1 through N from left to right.
Initially, all squares are white.
We also have N-1 painting machines, numbered 1 through N-1.
When operated, Machine i paints Square i and i+1 black.

Snuke will operate these machines one by one.
The order in which he operates them is represented by a permutation of (1, 2, ..., N-1), P, which means that the i-th operated machine is Machine P_i.

Here, the score of a permutation P is defined as the number of machines that are operated before all the squares are painted black for the first time, when the machines are operated in the order specified by P.
Snuke has not decided what permutation P to use, but he is interested in the scores of possible permutations.
Find the sum of the scores over all possible permutations for him.
Since this can be extremely large, compute the sum modulo 10^9+7.

Constraints

2 \leq N \leq 10^6

Input

Input is given from Standard Input in the following format:

N

Output

Print the sum of the scores over all possible permutations, modulo 10^9+7.

Sample Input 1

4

Sample Output 1

16

There are six possible permutations as P.
Among them, P = (1, 3, 2) and P = (3, 1, 2) have a score of 2, and the others have a score of 3.
Thus, the answer is 2 \times 2 + 3 \times 4 = 16.

Sample Input 2

2

Sample Output 2

1

There is only one possible permutation: P = (1), which has a score of 1.

Sample Input 3

5

Sample Output 3

84

Sample Input 4

100000

Sample Output 4

341429644

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import java.math.*;
import java.util.*;

public class Main {

	static class ModuloCombinatorics {
		/** maximal needed number, N itself is included **/
		final int N;

		/** prime modulo **/
		final int P;

		/** factorials **/
		final int[] fact;

		/** multiplicative inverses, take care to not touch inv[0] **/
		final int[] inv;

		/** inverse factorials **/
		final int[] invFact;

		public ModuloCombinatorics(int N, int P) {
			this.N = N;
			this.P = P;
			fact = new int[N + 1];
			fact[0] = 1;
			for (int i = 1; i <= N; i++) {
				fact[i] = (int) ((long) i * fact[i - 1] % P);
			}

			inv = new int[N + 1];
			inv[1] = 1;
			for (int i = 2; i <= N; i++) {
				inv[i] = P - (int) ((long) (P / i) * inv[P % i] % P);
			}

			invFact = new int[N + 1];
			invFact[0] = 1;
			for (int i = 1; i <= N; i++) {
				invFact[i] = (int) ((long) invFact[i - 1] * inv[i] % P);
			}
		}

		public int choose(int n, int k) {
			return (n < 0 || k < 0 || k > n) ? 0 : (int) ((long) fact[n]
					* invFact[k] % P * invFact[n - k] % P);
		}

		/** a^b modulo mod, mod is arbitrary **/
		static public int pow(int a, long b, int mod) {
			if (a < 0 || a >= mod || b < 0) {
				throw new IllegalArgumentException();
			}
			int ret = 1;
			for (; b > 0; b >>= 1) {
				if ((b & 1) == 1) {
					ret = (int) ((long) ret * a % mod);
				}
				a = (int) ((long) a * a % mod);
			}
			return ret;
		}

		/** a^b modulo P **/
		public int pow(int a, long b) {
			return pow(a, b, P);
		}
	}

	static final int P = 1_000_000_007;

	ModuloCombinatorics mc = new ModuloCombinatorics(1_000_010, P);

	int fast(int n) {
		if (n < 5) {
			return slow(n);
		}

		int diff = n - 2;

		long ret = 0;

		for (int twos = diff / 2; twos >= 0; twos--) {
			int ones = diff - twos * 2;

			long total = (long) mc.choose(ones + twos, ones)
					* (ones + twos - 1) % P;

			long total11;
			if (ones < 2) {
				total11 = 0;
			} else {
				total11 = (long) mc.choose(ones + twos - 2, ones - 2)
						* (ones + twos - 1) % P;
			}

			total -= total11;
			if (total < 0) {
				total += P;
			}

			// but those on the edge can be two
			total += 2 * mc.choose(ones + twos, ones) % P;

			int len = ones + twos + 1;

			ret += total * mc.fact[len - 1] % P * mc.fact[n - 1 - len] % P
					* len % P;
		}

		return (int) (ret % P);
	}

	int slow(int n) {
		int[] p = new int[n - 1];
		for (int i = 0; i < n - 1; i++) {
			p[i] = i;
		}

		int ret = 0;

		do {
			int[] done = new int[n];
			int left = n;

			for (int v : p) {
				if (left != 0) {
					ret++;
				}
				left -= (1 - done[v]) + (1 - done[v + 1]);
				done[v] = done[v + 1] = 1;
			}
		} while (nextPermutation(p));

		return ret;
	}

	static boolean nextPermutation(int[] a) {
		int n = a.length;
		int ptr = n - 1;
		while (ptr > 0 && a[ptr - 1] >= a[ptr]) {
			ptr--;
		}

		for (int i = ptr, j = n - 1; i < j; i++, j--) {
			int tmp = a[i];
			a[i] = a[j];
			a[j] = tmp;
		}

		if (ptr <= 0) {
			return false;
		}

		for (int i = ptr;; i++) {
			if (a[ptr - 1] < a[i]) {
				int tmp = a[ptr - 1];
				a[ptr - 1] = a[i];
				a[i] = tmp;
				return true;
			}
		}
	}

	void submit() {
		out.println(fast(nextInt()));
	}

	void test() {
		for (int n = 2; n <= 12; n++) {
			System.err.println(slow(n) + " " + fast(n));
		}
	}

	void stress() {
		for (int tst = 0;; tst++) {
			if (false) {
				throw new AssertionError();
			}
			System.err.println(tst);
		}
	}

	Main() throws IOException {
		is = System.in;
		out = new PrintWriter(System.out);
		submit();
		// stress();
		// test();
		out.close();
	}

	static final Random rng = new Random();
	static final int C = 5;

	static int rand(int l, int r) {
		return l + rng.nextInt(r - l + 1);
	}

	public static void main(String[] args) throws IOException {
		new Main();
	}

	private InputStream is;
	PrintWriter out;

	private byte[] buf = new byte[1 << 14];
	private int bufSz = 0, bufPtr = 0;

	private int readByte() {
		if (bufSz == -1)
			throw new RuntimeException("Reading past EOF");
		if (bufPtr >= bufSz) {
			bufPtr = 0;
			try {
				bufSz = is.read(buf);
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			if (bufSz <= 0)
				return -1;
		}
		return buf[bufPtr++];
	}

	private boolean isTrash(int c) {
		return c < 33 || c > 126;
	}

	private int skip() {
		int b;
		while ((b = readByte()) != -1 && isTrash(b))
			;
		return b;
	}

	String nextToken() {
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while (!isTrash(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	String nextString() {
		int b = readByte();
		StringBuilder sb = new StringBuilder();
		while (!isTrash(b) || b == ' ') {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	double nextDouble() {
		return Double.parseDouble(nextToken());
	}

	char nextChar() {
		return (char) skip();
	}

	int nextInt() {
		int ret = 0;
		int b = skip();
		if (b != '-' && (b < '0' || b > '9')) {
			throw new InputMismatchException();
		}
		boolean neg = false;
		if (b == '-') {
			neg = true;
			b = readByte();
		}
		while (true) {
			if (b >= '0' && b <= '9') {
				ret = ret * 10 + (b - '0');
			} else {
				if (b != -1 && !isTrash(b)) {
					throw new InputMismatchException();
				}
				return neg ? -ret : ret;
			}
			b = readByte();
		}
	}

	long nextLong() {
		long ret = 0;
		int b = skip();
		if (b != '-' && (b < '0' || b > '9')) {
			throw new InputMismatchException();
		}
		boolean neg = false;
		if (b == '-') {
			neg = true;
			b = readByte();
		}
		while (true) {
			if (b >= '0' && b <= '9') {
				ret = ret * 10 + (b - '0');
			} else {
				if (b != -1 && !isTrash(b)) {
					throw new InputMismatchException();
				}
				return neg ? -ret : ret;
			}
			b = readByte();
		}
	}
}