import java.util.Scanner;
public class Ex22 {
public static void main(String[] args) {
  Scanner s = new Scanner(System.in);
  int n = s.nextInt();
  Ex22 tfr = new Ex22();
  System.out.println(tfr.recursion(n));
 
}
 
public long recursion(int n) {
  long value = 0 ;
  if(n ==1 || n == 0) {
  value = 1;
  } else if(n > 1) {
  value = n * recursion(n-1);
  }
  return value;
}
 
}

public class lianxi22 {
public static void main(String[] args) {
    int n = 5;
  rec fr = new rec();
  System.out.println(n+"! = "+fr.rec(n));
}
}
class rec{
public long rec(int n) {
  long value = 0 ;
  if(n ==1 ) {
   value = 1;
  } else  {
   value = n * rec(n-1);
  }
  return value;
}
}