using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApp191 { class Program { static void Main(string[] args) { int n = int.Parse(Console.ReadLine()); int a = 1; while ((1 + a) * a / 2 < n) { a += 1; } Console.WriteLine(a); Console.ReadLine(); } } }