百练 2709 求出e的值

# include <stdio.h>
void main()
{
	double e=1,f=1;	
	int i,n;
	scanf("%d",&n);
	for(i=1;i<=n;i++)
	{	
		f*=i;
		e+=1.0/f;
	}
	printf("%.10f\n",e);
}