import java.util.*; |
public class Main { |
public static void main(String[] args) |
{ |
Scanner scan = new Scanner(System.in); |
int N = scan.nextInt(); |
int sum = 0 , i = 1 ; |
for (; i <= N; i++) |
{ |
int s = 1 ; |
for ( int j = 1 ; j <= i; j++) |
s *= j; |
sum += s; |
} |
System.out.println(sum); |
} |
} |