试了一下100000会爆0，

#include<iostream>
using namespace std;
unsigned long long point,ans=1,x=1,sum=2;
int main()
{
	cin>>point;
	if(point<4)
	{
		cout<<0<<endl;
		return 0;
	}
	if(point==4)
	{
		cout<<1<<endl;
		return 0;
	}
	for(int i=5;i<=point;i++)
	{
		ans*=i;
		if(ans%sum==0)
		{
				ans/=sum;
				sum++;
		}
	}
	cout<<ans<<endl;
	return 0;
}