#include <iostream>
using namespace std;

int Sum(int m)
{
	int sum = 0;
	while (m > 0)
	{
		int du = m % 10;
		sum += du;
		m = m / 10;
	}
	return sum;
}
int TinhFx(int n)
{
	int p = 1;
	if (n <= 9)
	{
		for (int i = 1; i <= n; i++)
		{
			p *= i;
		}
		return p;
	}
	else
	{
		for (int i = 1; i <= n; i++)
		{
			p *= i;
		}
		return Sum(p);
	}
}
void main()
{
	int n;
	do {
		cout << "Nhap n (n>=1) =";
		cin >> n;
	} while (n < 1);
	cout << "F(" << n << "!) = " << TinhFx(n);
}