#include<bits/stdc++.h>
using namespace std;
int main(){
	int a=1,n,c=0,d=1;
	cin>>n;
	while(n>=d){
		a=a*d;
		d+=1; 
		
		
	
		
	}
	cout<<a;

	
	


		
	return 0;
}
/**************************************************************
	Problem: 1004
	User: cyp
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/