using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace No480 { public class Program { static void Main(string[] args) { int n = int.Parse(Console.ReadLine()); System.Console.WriteLine(NewMethod(n)); } public static int NewMethod(int n) { int sum = (1 + n) * n / 2; return sum; } } }