View Code of Problem 3834

#include<string>
#include<cstring>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<vector>
#include<cstring>
using namespace std;
//int a[1000][1000];
#include<string>
#include<cstring>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<vector>
#include<cstring>
using namespace std;
//int a[1000][1000];
long long int cal(int a, int b)
{
	int temp = b;
	int temp1 = a;
	long long int num = 1;
	long long int num1 = 1;
	while (temp--)
	{
		num *= a;
		a--;
	}
	temp=b;
	while (temp--)
	{
		num1 *= b;
		b--;
	}
	return num/num1;
}
int main()
{
	int n;
	while (cin >> n)
	{
		int z = 0;
		long long sum = 0;
		while (z <= n)
		{
			sum += pow(2, n - z)*cal(n, z);
			z += 2;
		}
		cout << sum << endl;
	}
}