#include <iostream>
using namespace std;
int main(){
    int n,i,s=1;
    cin>>n;
    i=1;
    while(i<=n){
        s=s*i;
        i=i+1; 
    }
    cout<<s; 
}
/**************************************************************
	Problem: 1066
	User: wenda
	Language: C++
	Result: Wrong Answer
****************************************************************/