Calculate the formula

Problem Description

You just need to calculate the sum of the formula: 1^2+3^2+5^2+……+ n ^2.

Input

In each case, there is an odd positive integer n.

Output

Print the sum. Make sure the sum will not exceed 2^31-1

Sample Input

3

Sample Output

10

用普通的做法会超时，只能用公式算n*(4*n*n-1)/3(其中n为第几个数)，还有题目明明说好结果在int范围内的，但是必须用__int64才能过，郁闷。。。

 1 #include <stdio.h>
 2
 3 int main(){
 4     __int64 number;
 5     __int64 n;
 6     __int64 result;
 7
 8     while(scanf("%I64d",&number)!=EOF){
 9         n=(number+1)/2;
10
11         result=n*(4*n*n-1)/3;
12         printf("%I64d\n",result);
13
14     }
15     return 0;
16 }