import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Calendar;
import java.util.Scanner;

public class TinhGiaiThua1 {
	public static void main(String[] args) {
		File file = new File("KETQUA2.txt");
		try (FileWriter fw = new FileWriter(file, true);
				BufferedWriter bf = new BufferedWriter(fw);
				PrintWriter pw = new PrintWriter(file)) {
			Scanner scanner = new Scanner(System.in);
			System.out.println("Nhap so can tinh giai thua: ");
			int n = scanner.nextInt();
			long timeBegin = Calendar.getInstance().getTimeInMillis();
			String x = giaithua(n);
			long timeEnd = Calendar.getInstance().getTimeInMillis();
			pw.println("Thoi gian thuc hien : "+(timeEnd - timeBegin));
			pw.println("Ket qua :" + x);
		} catch (IOException e) {
			// TODO: handle exception
		}

	}

	public static String giaithua(int n) {
		String sb = "" ;
		int[] A = new int[500000];
		int m = 1;
		long r = 0;
		long q;
		A[0] = 1;
		for (int i = 2; i <= n; i++) {
			for (int j = 0; j < m; j++) {
				q = r;
				r = (A[j] * i + r) / 10;
				A[j] = (int) ((A[j] * i + q) % 10);
			}
			while (r > 0) {
				A[m] = (int) (r % 10);
				m++;
				r = r / 10;
			}
		}
		for (int i = m - 1; i >= 0; i--) {
			sb += A[i];
		}
		return sb;
	}
}