public class Solution {

    public int ArrangeCoins(int n) {

        //convert int to long to prevent integer overflow

            long nLong = (long)n;

            long st = ;

            long ed = nLong;

            long mid = ;

            while (st <= ed)

            {

                mid = st + (ed - st) / ;

                if (mid * (mid + ) <=  * nLong)

                {

                    st = mid + ;

                }

                else

                {

                    ed = mid - ;

                }

            }

            return (int)(st - );

    }

}