/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.scanner;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		      Scanner sc =new Scanner(System.in);
         long x;
         long y=1;
         x=sc.nextInt();
         if(x>=2 && x<=100){
         for(int i=1;i<=x;i++){
             y*=i;
         }
         System.out.println(y);
         }
         else {
         System.out.println("error");
         }
	  }
	}
}

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

NQ==

5