Problem:
Score : 400 points

Problem Statement

Snuke has decided to play a game using cards.
He has a deck consisting of N cards. On the i-th card from the top, an integer A_i is written.

He will perform the operation described below zero or more times, so that the values written on the remaining cards will be pairwise distinct. Find the maximum possible number of remaining cards. Here, N is odd, which guarantees that at least one card can be kept.

Operation: Take out three arbitrary cards from the deck. Among those three cards, eat two: one with the largest value, and another with the smallest value. Then, return the remaining one card to the deck.

Constraints

3 ≦ N ≦ 10^{5}

N is odd.

1 ≦ A_i ≦ 10^{5}

A_i is an integer.

Input

The input is given from Standard Input in the following format:

N
A_1 A_2 A_3 ... A_{N}

Output

Print the answer.

Sample Input 1

5
1 2 1 3 7

Sample Output 1

3

One optimal solution is to perform the operation once, taking out two cards with 1 and one card with 2. One card with 1 and another with 2 will be eaten, and the remaining card with 1 will be returned to deck. Then, the values written on the remaining cards in the deck will be pairwise distinct: 1, 3 and 7.

Sample Input 2

15
1 3 5 2 1 3 2 8 8 6 2 6 11 1 1

Sample Output 2

7

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection.Emit;
using System.Security.Cryptography;
using System.Text;
using System.Threading;
namespace Program{
    class MainClass{
        ////////////////////////////////////////////////////////////
        private int N;
        private int[] A;
        void Solve(){
            N = io.Int;
            A = io.arrInt;
            var aa = new AssociativeArray<int>(A);
            var keyNum = aa.KeyNum;
            var ans = 0;
            if(keyNum.Odd()) ans = keyNum;
            else ans = keyNum - 1;
            io.o(ans);
        }

        ////////////////////////////////////////////////////////////
        public static void Main() { new MainClass().Stream(); }
        IO io = new IO();
        Mat mat = new Mat();
        void Stream(){
            Solve();
            //Test();
            io.writeFlush();
        }
        void Test() { }
        #region MockMacro
        //cannot use break,continue,goto
        void FOR(int a, int b, Action<int> act){
            for(int i = a; i < b; ++i) act(i);
        }
        void FORR(int a, int b, Action<int> act){
            for(int i = a - 1; i >= b; --i) act(i);
        }
        #endregion
        ////////////////////////////////////////////////////////////
    }
    #region default
    class IO{
        string[] nextBuffer;
        int BufferCnt;
        char[] cs = new char[]{' '};
        StreamWriter sw = new StreamWriter(Console.OpenStandardOutput()){AutoFlush = false};
        public IO(){
            nextBuffer = new string[0];
            BufferCnt = 0;
            Console.SetOut(sw);
        }
        public string Next(){
            if(BufferCnt < nextBuffer.Length) return nextBuffer[BufferCnt++];
            string st = Console.ReadLine();
            while(st == "") st = Console.ReadLine();
            nextBuffer = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            BufferCnt = 0;
            return nextBuffer[BufferCnt++];
        }
        public string String => Next();
        public char Char => char.Parse(String);
        //public int Int => int.Parse(String);
        public int Int => String.toInt();
        public long Long => String.toLong();
        public double Double => double.Parse(String);
        public string[] Arr => Console.ReadLine().Split(' ');
        public char[] arrChar => Array.ConvertAll(Arr, char.Parse);
        public int[] arrInt => Array.ConvertAll(Arr, int.Parse);
        //public int[] arrInt => arr.Select(v => v.toInt()).ToArray();
        //public long[] arrLong => Array.ConvertAll(arr, long.Parse);
        public long[] arrLong => Arr.Select(v => v.toLong()).ToArray();
        public double[] arrDouble => Array.ConvertAll(Arr, double.Parse);
        public T i<T>() { return suitType<T>(String); }
        public void i<T>(out T v) { v = suitType<T>(String); }
        public void i<T, U>(out T v1, out U v2){
            i(out v1);
            i(out v2);
        }
        public void i<T, U, V>(out T v1, out U v2, out V v3){
            i(out v1);
            i(out v2);
            i(out v3);
        }
        public void i<T, U, V, W>(out T v1, out U v2, out V v3, out W v4){
            i(out v1);
            i(out v2);
            i(out v3);
            i(out v4);
        }
        public void i<T, U, V, W, X>(out T v1, out U v2, out V v3, out W v4, out X v5){
            i(out v1);
            i(out v2);
            i(out v3);
            i(out v4);
            i(out v5);
        }
        public void ini<T>(out T[] a, int n){
            a = new T[n];
            for(int i = 0; i < n; ++i) a[i] = suitType<T>(String);
        }
        public void ini<T, U>(out T[] a, out U[] b, int n){
            a = new T[n];
            b = new U[n];
            for(int i = 0; i < n; ++i){
                a[i] = i<T>();
                b[i] = i<U>();
            }
        }
        public void ini<T, U, V>(out T[] a, out U[] b, out V[] c, int n){
            a = new T[n];
            b = new U[n];
            c = new V[n];
            for(int i = 0; i < n; ++i){
                a[i] = i<T>();
                b[i] = i<U>();
                c[i] = i<V>();
            }
        }
        public void ini<T, U>(out Tuple<T, U>[] t, int n){
            t = new Tuple<T, U>[n];
            for(int j = 0; j < n; ++j){
                T i1;
                U i2;
                i(out i1);
                i(out i2);
                t[j] = Tuple.Create(i1, i2);
            }
        }
        public void ini<T, U, V>(out Tuple<T, U, V>[] t, int n){
            t = new Tuple<T, U, V>[n];
            for(int j = 0; j < n; ++j){
                T i1;
                U i2;
                V i3;
                i(out i1);
                i(out i2);
                i(out i3);
                t[j] = Tuple.Create(i1, i2, i3);
            }
        }
        public void ini<T>(out T[,] a, int h, int w){
            a = new T[h, w];
            for(int i = 0; i < h; ++i) for(int j = 0; j < w; ++j) a[i, j] = i<T>();
        }
        public void o<T>(T v) { Console.WriteLine(v); }
        public void o<T>(params T[] a) { Array.ForEach(a, n => o(n)); }
        public void o<T>(T[,] a){
            int a0 = a.GetLength(0), a1 = a.GetLength(1);
            for(int i = 0; i < a0; ++i){
                for(int j = 0; j < a1 - 1; ++j) Console.Write(a[i, j] + " ");
                Console.WriteLine(a[i, a1 - 1]);
            }
        }
        public void o<T, U>(Dictionary<T, U> dic){
            o("Show(key:" + dic.Keys.Count + ")");
            foreach(var kp in dic.OrderBy(kp => kp.Key).ToDictionary(kp => kp.Key, kp => kp.Value)) o(kp.Key + "\t" + kp.Value);
            o("--- ---- ---");
        }
        public void YN(bool f) { o(f ? "YES" : "NO"); }
        public void Yn(bool f) { o(f ? "Yes" : "No"); }
        public void yn(bool f) { o(f ? "yes" : "no"); }
        public void ol<T>(params T[] a) { o(connect<T>(a)); }
        public void or<T>(T a) { Console.Write(a); }
        public void br() { o(""); }
        public void writeFlush() { Console.Out.Flush(); }
        private string connect<T>(params T[] s) { return string.Join(" ", s); }
        private bool typeEQ<T, U>() { return typeof(T).Equals(typeof(U)); }
        private T convertType<T, U>(U v) { return (T) Convert.ChangeType(v, typeof(T)); }
        private T suitType<T>(string s){
            if(typeEQ<T, int>()) return convertType<T, int>(int.Parse(s));
            if(typeEQ<T, long>()) return convertType<T, long>(long.Parse(s));
            if(typeEQ<T, double>()) return convertType<T, double>(double.Parse(s));
            if(typeEQ<T, char>()) return convertType<T, char>(char.Parse(s));
            return convertType<T, string>(s);
        }
    }
    class Mat{
        public long mod = 1000000007;//10^9+7
        public long Pow(long a, long b){
            if(b == 0) return 1;
            if(b % 2 == 1) return (a % mod * Pow(a % mod, b - 1) % mod) % mod;
            else return Pow(a * a % mod, b / 2) % mod;
        }
        public long Fact(long n){
            long ret = 1;
            for(long i = 1; i <= n; i++) ret = (ret * i) % mod;
            return ret;
        }
        public long ModC(long n, long r){
            if(r == 0 || n == r) return 1;
            if(n == 0) return 0;
            if(n < 0 || n < r) throw new ArgumentException("n,r invalid");
            else return (Fact(n) % mod * Pow((Fact(n - r) % mod * Fact(r) % mod) % mod, mod - 2) % mod) % mod;
        }
        public long[,] C(int N){
            long[,] Co = new long[N + 1, N + 1];
            (N + 1).REP(i => (i + 1).REP(j => Co[i, j] = (j == 0 || j == i) ? 1L : Co[i - 1, j - 1] + Co[i - 1, j]));
            return Co;
        }
        public long DupC(long n, long r) { return ModC(n + r - 1, r); }
        public long P(long n, long r) { return Fact(n) / (Fact(n - r)); }//test
        public bool isPrime(long n){
            if(n == 2) return true;
            if(n < 2 || n % 2 == 0) return false;
            for(long v = 3; v <= (long) Math.Sqrt(n); v += 2) if(n % v == 0) return false;
            return true;
        }
        public long LCM(long a, long b) { return a * (b / GCD(a, b)); }
        public long LCM(params long[] a) { return a.Aggregate((v, n) => LCM(v, n)); }
        public long GCD(long a, long b){
            if(a < b) Swap(ref a, ref b);
            return b == 0 ? a : GCD(b, a % b);
        }
        public long GCD(params long[] array) { return array.Aggregate((v, n) => GCD(v, n)); }
        public T Max<T>(params T[] a) { return a.Max(); }
        public T Min<T>(params T[] a) { return a.Min(); }
        public void Swap<T>(ref T a, ref T b){
            T tmp = a;
            a = b;
            b = tmp;
        }
        public double Dis(int x1, int y1, int x2, int y2) { return Math.Sqrt(Math.Pow((x2 - x1), 2) + Math.Pow((y2 - y1), 2)); }
        public int mDis(int x1, int y1, int x2, int y2) { return Math.Abs(x1 - x2) + Math.Abs(y1 - y2); }
        public int[] DigArr(int n){
            int[] ret = new int[Digit(n)];
            ret.Length.REP(i => ret[i] = DigVal(n, i + 1));
            return ret;
        }
        public long DigArr2Num(IEnumerable<int> enu) { return enu.Aggregate((v, n) => v * 10 + n); }
        public int Digit(long n) { return (n == 0) ? 1 : (int) Math.Log10(n) + 1; }
        public int DigVal(int n, int dig) { return (n % (int) Pow(10, dig)) / (int) Pow(10, dig - 1); }
        public long Tousa(long a, long d, long n) { return a + (n - 1) * d; }
        public long TousaSum(long a, long d, long n) { return n * (2 * a + (n - 1) * d) / 2; }
        public long[] EnuDivsor(long N){
            var ret = new SortedSet<long>();
            for(long i = 1; i * i <= N; i++)
                if(N % i == 0){
                    ret.Add(i);
                    ret.Add(N / i);
                }
            return ret.ToArray();
        }
        public Dictionary<long, long> PrimeFactor(long n){
            var ret = new Dictionary<long, long>();
            for(int i = 2; i * i <= n; ++i){
                if(!ret.ContainsKey(i)) ret[i] = 0;
                while(n % i == 0){
                    ++ret[i];
                    n /= i;
                }
            }
            return ret.Where(kp => kp.Value != 0).ToDictionary(kp => kp.Key, kp => kp.Value);
        }
    }
    #endregion
    class AssociativeArray<T> : IEnumerable{
        public Dictionary<T, int> dic;
        public AssociativeArray() { dic = new Dictionary<T, int>(); }
        public AssociativeArray(params T[] a){
            dic = new Dictionary<T, int>();
            Add(a);
        }
        public void Add(T a){
            if(!conK(a)) dic[a] = 0;
            dic[a]++;
        }
        public void Add(params T[] a){
            a.Length.REP(i =>{
                if(!conK(a[i])) dic[a[i]] = 0;
                dic[a[i]]++;
            });
        }
        public void Set(T k, int v){
            if(!dic.ContainsKey(k)) dic[k] = 0;
            dic[k] = v;
        }
        public void Remove(params T[] a){
            a.Length.REP(i =>{
                if(conK(a[i])) dic.Remove(a[i]);
            });
        }
        public T[] Keys() { return dic.Keys.ToArray<T>(); }
        public int Val(T k) { return (dic.ContainsKey(k)) ? dic[k] : 0; }
        public int ValSum => dic.Values.Sum();
        public int KeyNum => dic.Keys.Count;
        public int MaxVal => dic.Values.Max();
        public int MinVal => dic.Values.Min();
        public T MaxKey => MaxK();
        public T MinKey => MinK();
        public T MaxK(){
            var maxV = MaxVal;
            return dic.First(d => d.Value == maxV).Key;
        }
        public T MinK(){
            var minV = MinVal;
            return dic.First(d => d.Value == minV).Key;
        }
        public T[] MaxKeys(){
            var maxV = MaxVal;
            return dic.Where(kp => kp.Value == maxV).ToDictionary(kp => kp.Key, kp => kp.Value).Keys.ToArray();
        }
        public T[] MinKeys(){
            var minV = MinVal;
            return dic.Where(kp => kp.Value == minV).ToDictionary(kp => kp.Key, kp => kp.Value).Keys.ToArray();
        }
        public bool conK(T k) { return dic.ContainsKey(k); }
        public bool anyK(params T[] k) { return k.Any(key => conK(key)); }
        public bool allK(params T[] k) { return k.All(key => conK(key)); }
        public T[] ValueSortedKey(bool inc = true) { return (inc ? (dic.OrderBy(kp => kp.Value)) : (dic.OrderByDescending(kp => kp.Value))).ThenBy(kp => kp.Key).ToDictionary(kp => kp.Key, kp => kp.Value).Keys.ToArray(); }
        public IEnumerator GetEnumerator(){
            foreach(var kp in dic) yield return kp;
        }
        //:sort->array
    }
    #region Ex
    static class StringEX{
        public static string Reversed(this string s) { return string.Join("", s.Reverse()); }
        public static string Repeat(this string s, int n) { return string.Concat(Enumerable.Repeat(s, n).ToArray()); }
        public static int toInt(this string s){
            int n;
            return (int.TryParse(s.TrimStart('0'), out n)) ? n : 0;
        }
        public static int toInt(this char c) { return toInt(c.ToString()); }
        public static int toInt(this char[] c) { return toInt(new string(c)); }
        public static long[] toLong(this int[] a) { return a.Select(v => (long) v).ToArray(); }
        public static long[,] toLong(this int[,] m){
            var h = m.GetLength(0);
            var w = m.GetLength(1);
            var ret = new long[h, w];
            for(int i = 0; i < h; ++i) for(int j = 0; j < w; ++j) ret[i, j] = (long) m[i, j];
            return ret;
        }
        public static long toLong(this string s){
            long n;
            return (long.TryParse(s.TrimStart('0'), out n)) ? n : (long) 0;
        }
        public static long toLong(this char c) { return toLong(c.ToString()); }
        public static long toLong(this char[] c) { return toLong(new string(c)); }
        public static string toString(this char[] c) { return new string(c); }
    }
    static class NumericEx{
        public static string pad0<T>(this T v, int n) { return v.ToString().PadLeft(n, '0'); }
        public static double RoundOff(this double v, int n) { return Math.Round(v, n - 1, MidpointRounding.AwayFromZero); }
        public static double RoundUp(this double v) { return Math.Ceiling(v); }
        public static double RoundDown(this double v) { return Math.Floor(v); }
        public static bool Odd(this int v) { return v % 2 != 0; }
        public static bool Odd(this long v) { return v % 2 != 0; }
        public static void REP(this int v, Action<int> act){
            for(int i = 0; i < v; ++i) act(i);
        }
        public static void REPR(this int v, Action<int> act){
            for(int i = v - 1; i >= 0; --i) act(i);
        }
    }
    static class ArrayEX{
        public static T[] Sort<T>(this T[] a){
            Array.Sort(a);
            return a;
        }
        public static T[] SortR<T>(this T[] a){
            Array.Sort(a);
            Array.Reverse(a);
            return a;
        }
        public static void Set<T>(this T[] a, T v) { a.Length.REP(i => a[i] = v); }
        public static void Set<T>(this T[,] a, T v) { a.GetLength(0).REP(i => a.GetLength(1).REP(j => a[i, j] = v)); }
        public static int[] toIntArr(this string a) { return a.Select(c => c.toInt()).ToArray(); }
        public static int[] toIntArr(this string[] a) { return Array.ConvertAll(a, int.Parse); }
        public static long[] toLongArr(this string a) { return a.Select(c => c.toLong()).ToArray(); }
        public static long[] toLongArr(this string[] a) { return Array.ConvertAll(a, long.Parse); }
        public static double[] toDoubleArr(this string[] a) { return Array.ConvertAll(a, double.Parse); }
        public static char[] toCharArr(this string[] a) { return Array.ConvertAll(a, char.Parse); }
        public static int LowerBound<T>(this T[] a, T x) where T : IComparable{
            //Array.Sort(a);
            int lb = -1, ub = a.Length;
            while(ub - lb > 1){
                var mid = (ub + lb) / 2;
                if(a[mid].CompareTo(x) >= 0) ub = mid;
                else lb = mid;
            }
            return ub;
        }
        public static int testLowerBound<T>(this T[] a, T x) where T : IComparable{
            int lb = -1, ub = a.Length;
            while(Math.Abs(ub - lb) > 1){
                var mid = (ub + lb) >> 1;
                if(a[mid].CompareTo(x) >= 0) ub = mid;
                else lb = mid;
            }
            return ub;
        }
        public static int UpperBound<T>(this T[] a, T x) where T : IComparable{
            //Array.Sort(a);
            int lb = -1, ub = a.Length;
            while(ub - lb > 1){
                var mid = (ub + lb) / 2;
                if(a[mid].CompareTo(x) > 0) ub = mid;
                else lb = mid;
            }
            return ub;
        }
        public static int testUpperBound<T>(this T[] a, T x) where T : IComparable{
            //Array.Sort(a);
            int lb = -1, ub = a.Length;
            while(Math.Abs(ub - lb) > 1){
                var mid = (ub + lb) >> 1;
                if(a[mid].CompareTo(x) > 0) ub = mid;
                else lb = mid;
            }
            return ub;
        }
    }
    #endregion
}