UVa : 913 (Joana and the Odd Numbers)

// http://uva.onlinejudge.org/external/9/913.html
// Runtime: 2.292s
// Tag: math

// @BEGIN_OF_SOURCE_CODE

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <sstream>
#include <cmath>
#include <bitset>
#include <utility>
#include <set>
#include <numeric>
#include <ctime>

#define Inf 2147483647
#define Pi acos(-1.0)
#define N 1000000
#define LL long long

const double EPS = 1e-9;
inline bool Equal(double a, double b) { return abs(a-b) < EPS; }
inline LL Power(int b, int p) { LL ret = 1; for ( int i = 1; i <= p; i++ ) ret *= b; return ret; }
const int dr [] = {-1, -1, 0, 1, 1, 1, 0, -1};
const int dc [] = {0, 1, 1, 1, 0, -1, -1, -1};

#define F(i, a, b) for( int i = (a); i < (b); i++ )
#define Fs(i, sz) for( size_t i = 0; i < sz.size (); i++ )
#define Fe(i, x) for(typeof (x.begin()) i = x.begin(); i != x.end (); i++)
#define Set(a, s) memset(a, s, sizeof (a))
#define max(a, b)  (a < b ? b : a)
#define min(a, b)  (a > b ? b : a)

using namespace std;

int main ()
{
	int n;

	while ( scanf ("%d", &n) != EOF ) {
		int lineNumber = n / 2;
		LL num = 6;
		LL next = 1;

		for ( int i = 0; i < lineNumber; i++ ) {
			next += num;
			num += 4;
		}

		printf ("%lld\n", next + (next - 2) + (next - 4));

	}

	return 0;
}