#include<bits/stdc++.h>
using namespace std;
int a[1200],c[1200];
int n,m;
int cheng(int x){
	if(x == 1){
		a[1] = 1;
	}else{
		int c = 0;
		for(int i = 1;i <= 1000;i ++){
			a[i] *= x;
			a[i] += c;
			c = a[i] / 10;
			a[i] %= 10;
		}
	}
}
int jia(){
	for(int i = 1;i <= 1000;i ++){
		c[i] += a[i];
		c[i + 1] += c[i] / 10;
		c[i] %= 10;
	}
}
int main(){
	cin>>n;
	for(int i = 1;i <= n;i ++){
		cheng(i);
		jia();
	}
	int len = 1000;
	while(c[len] == 0){
		len --;
	}
	for(int i = len;i >= 1;i --){
		cout<<c[i];
	}
	return 0;
} 

结果