import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		System.out.println("请输所求阶乘累加的个数：");
		int n = input.nextInt();
		long test,sum = 0;
		
		for(int i=1; i<=n; i++) {
			test = 1;
			for(int j=1; j<=i; j++) {
				test *= j;
			}
			sum += test;
		}
		System.out.println("累加的和为：" + sum);
	}
}