#include <iostream>
using namespace std; 
int main(){
   int i,s = 1,n;
   cin>>n;
   for(i = 1;i <= n;i++){
      s = s* i;
   }
    
   cout<<s<<endl;
   return 0;
}

/**************************************************************
	Problem: 1004
	User: zhuangsongyu
	Language: C++
	Result: Accepted
	Time:19 ms
	Memory:2072 kb
****************************************************************/