#include<iostream> //输入函数库 #include<iomanip> #include<cmath> //数学函数库 #include<cstdio> #include<ctime> #include<cstring> #include<cstdlib> #include<string> #include<stdlib.h> #include<sys/time.h> using namespace std; int main(){ int x,y=1; cin>>x; for(int i=1;i<=x;i++){ y=y*i; } cout<<y; return 0; }