class sum
{
public:
    sum()
    {
        _sum+=_i;
        ++_i;
    }
    static int GetSum()
    {
        return _sum;
    }
private:
    static int _i;
    static int _sum;
};
int sum::_i=1;
int sum::_sum=0;
class Solution {
public:
    int Sum_Solution(int n) {
        sum arr[n];
        return sum::GetSum();
    }
};