using System; using System.Linq; using System.Collections.Generic; using System.Text.RegularExpressions; using System.Text; public class Program { public void Proc() { Reader.IsDebug = false; bool ans = this.GetAns(); Console.WriteLine(ans?"YES":"NO"); } private bool GetAns() { long[] inpt = Reader.ReadLine().Split(' ').Select(a=>long.Parse(a)).ToArray(); int itemCount = (int)inpt[0]; long nokori = inpt[1]; int[] items = Reader.ReadLine().Split(' ').Select(a=>int.Parse(a)).ToArray(); Dictionary<int, int> numIndex = new Dictionary<int, int>(); Dictionary<int, int> indexNum = new Dictionary<int, int>(); for(int i=0; i<items.Length; i++) { indexNum.Add(i, items[i]); numIndex.Add(items[i], i); } for(int i=1; i<=itemCount; i++) { if(items[i-1] == i) { continue; } if(nokori <= 0) { return false; } int idx = numIndex[i]; int num = items[i-1]; items[i-1] = items[idx]; items[idx] = num; numIndex[i] = i-1; numIndex[num] = idx; indexNum[i-1] = i; indexNum[idx] = num; nokori--; } return nokori%2==0; } public class Reader { public static bool IsDebug = true; private static System.IO.StringReader SReader; private static string InitText = @" "; public static string ReadLine() { if(IsDebug) { if(SReader == null) { SReader = new System.IO.StringReader(InitText.Trim()); } return SReader.ReadLine(); } else { return Console.ReadLine(); } } } public static void Main(string[] args) { Program prg = new Program(); prg.Proc(); } }