class Main{
	public static void main (String[] args) throws java.lang.Exception 	{
		java.util.Scanner i = new java.util.Scanner(System.in);
		int n = i.nextInt();
		long factorial = 1;
    	for(int k = 1; k <= n; k++) {
        	factorial *= k;
    	}
    	System.out.print(factorial);
	}
}