import java.io.;
import java.util.;
public class Main{
public static void main(String args[]) {
Scanner cin = new Scanner(System.in);
var n = cin.nextInt();
System.out.println(fact(n));
}
public static int fact(int n){
int res = 1;
for(int i = 1; i <= n; i++){
res = res * i;
}
return res;
}
}