Problem:
Score : 300 points

Problem Statement

Given is a sequence of integers A_1, A_2, ..., A_N.
If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

2 ≤ N ≤ 200000

1 ≤ A_i ≤ 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Numerics;
using System.Linq;
using System.Text;
using static System.Math;

class MainClass
{

    public static void Main(string[] args)
    {
        var N = LnInt();
        var hash = new HashSet<long>(LnLngs());
        print(N == hash.Count ? "Yes" : "No");
    }

public static long SumAtoB(long a,long b){var length = b - a + 1;return (a + b) * (length / 2) + (length % 2 == 1 ? (a + b) / 2 : 0);}
public static long PowLite(long n, long p, int mod = (int)1e9 + 7){long ans = 1;long now = n;for (; p > 0; p >>= 1){if ((p & 1) == 1){ans *= now;ans %= mod;}now *= now;now %= mod;}return ans;}
public static void print(object obj) { Console.WriteLine(obj); }
public static long Gcd(long a, long b) { if (a > b) { var r = a % b; if (r == 0) return b; else return Gcd(b, r); } else { var r = b % a; if (r == 0) return a; else return Gcd(a, r); } }
public static int Gcd(int a, int b) { if (a > b) { var r = a % b; if (r == 0) return b; else return Gcd(b, r); } else { var r = b % a; if (r == 0) return a; else return Gcd(a, r); } }
public static int[] LnInts() { var vs = Console.ReadLine().Trim().Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); var ins = new int[vs.Length]; for (int i = 0; i < vs.Length; i++) ins[i] = int.Parse(vs[i]); return ins; }
public static int LnInt() { var vs = Console.ReadLine().Trim(); return int.Parse(vs); }
public static long[] LnLngs() { var vs = Console.ReadLine().Trim().Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); var ins = new long[vs.Length]; for (int i = 0; i < vs.Length; i++) ins[i] = long.Parse(vs[i]); return ins; }
public static long LnLng() { var vs = Console.ReadLine().Trim(); return long.Parse(vs); }
public static string[] LnStrs() { var vs = Console.ReadLine().Trim().Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); return vs; }
public static string LnStr() { var vs = Console.ReadLine().Trim(); return vs; }
public static List<T[]> AllPermutation<T>(params T[] array) where T : IComparable{var a = new List<T>(array).ToArray();var res = new List<T[]>();res.Add(new List<T>(a).ToArray());var n = a.Length;var next = true;while (next){next = false;int i;for (i = n - 2; i >= 0; i--){if (a[i].CompareTo(a[i + 1]) < 0) break;}if (i < 0) break;var j = n;do{j--;} while (a[i].CompareTo(a[j]) > 0);if (a[i].CompareTo(a[j]) < 0){var tmp = a[i];a[i] = a[j];a[j] = tmp;Array.Reverse(a, i + 1, n - i - 1);res.Add(new List<T>(a).ToArray());next = true;}}return res;}}