import java.math.BigInteger;
import java.util.Scanner;
public class T_1402_Cocktails {
public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    BigInteger a[]=new BigInteger[30];
    BigInteger p=BigInteger.ONE;
    a[0]=BigInteger.ONE;
    for (int i = 1; i <=21; i++) {
        p=p.multiply(new BigInteger(i+""));
        a[i]=new BigInteger(p+"");
    }
    BigInteger sum=BigInteger.ZERO;
    for (int i = 0; i <=n-2; i++)
        sum=sum.add(a[n].divide(a[i]));
    System.out.println(sum);
}
}

I don't think so !!

Edited by author 11.12.2018 11:44