// 遞迴求階乘和 
#include <stdio.h>

double fact(int n);		// 遞迴求階乘 

double sum(int n);		// 遞迴求和 

int main(void)
{
	int n;
	
	printf("請輸入一個整數n(n>0且n<=10):");
	scanf("%d", &n);
	
	if (n == 1)
	{
		printf("1!=%.0f\n", sum(n));
	}
	else if (n == 2)
	{
		printf("1!+2!=%.0f\n", sum(n));
	}
	else if (n == 3)
	{
		printf("1!+2!+3!=%.0f\n", sum(n));
	}
	else 
	{
		printf("1!+2!+...+%d!=%.0f\n", n, sum(n));
	}
	
	return 0;
}

double fact(int n)
{
	double result;
	
	if (n == 1)
	{
		result = 1;
	}
	else
	{
		result = n*fact(n-1);
	}
	
	return result;
}

double sum(int n)
{
	double result;
	
	if (n == 1)
	{
		result = fact(1);
	}
	else
	{
		result = fact(n)+sum(n-1);
	}
	
	return result;
}