#include <iostream>
#include <algorithm>

using namespace std;
const int N = 1005;

int f[N],b[N];
int n;

int main()
{
	f[0] = 1, b[0] = 1;
	cin >> n;

	for (int i = 2; i <= n; i++)
	{
		for (int j = 0; j < N; j++)
		{
			f[j] *= i;//计算阶乘
		}

		for (int j = 0; j < N; j++)
		{
			if (f[j] > 9)
			{
				f[j + 1] += f[j] / 10;
				f[j] %= 10;
			}
		}

		for (int j = 0; j < N; j++)
		{
			b[j] += f[j];//计算阶乘和
			if (b[j] > 9)
			{
				b[j + 1] += b[j] / 10;
				b[j] %= 10;
			}
		}
	}
	int t = N;
	while (!b[t] && t >= 0)t--;

	for (int i = t; i >= 0; i--)cout << b[i];
	cout << endl;

	return 0;
}