Problem:
Score : 600 points

Problem Statement

Given is an integer N.
Find the minimum possible positive integer k such that (1+2+\cdots+k) is a multiple of N.
It can be proved that such a positive integer k always exists.

Constraints

1 \leq N \leq 10^{15}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer in a line.

Sample Input 1

11

Sample Output 1

10

1+2+\cdots+10=55 holds and 55 is indeed a multple of N=11.
There are no positive integers k \leq 9 that satisfy the condition, so the answer is k = 10.

Sample Input 2

20200920

Sample Output 2

1100144

Solution in C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;

namespace AtCoderConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            //入力
            decimal N = int.Parse(Console.ReadLine());
            decimal k = 1;
            while (true)
            {
                decimal sum = k * (k + 1) / 2;
                if (sum % N == 0)
                {
                    Console.WriteLine(k);
                    break;
                }
                k++;
            }
        }
    }
}