Zzuli:1054 monkeys eat peaches

Title Description

Wukong picked some peaches on the first day , Eat half immediately , Not yet , Eat another one , The next day, he ate half of the remaining peaches and more than one , After that, eat more than half of the rest of the previous day every day , To the first n One day when I was ready to eat, there was only one peach left . Smart you , Please help Wukong calculate , How many peaches did he have when he started eating on the first day ？

Input

Enter a number n（1<=n<=30）.

Output

Output the number of peaches in the first day .

The sample input  Copy

3

Sample output  Copy

10

#include <stdio.h>
int main()
{
	int n,i,sum=1;
	scanf("%d",&n);
	for(i=1;i<n;i++)
	{
		sum=2*(sum+1);
	}
	printf("%d",sum);
	return 0;
}