Sock Merchant - HackerRank

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;

public class Sock_Merchant {

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		int arrCnt = Integer.parseInt(br.readLine());
		
		int result = 0;
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		
		Map<Integer, Integer> map = new HashMap<Integer, Integer>();
		
		for(int i  = 0 ; i < arrCnt ; i++){
			int num = Integer.parseInt(st.nextToken());
			if(!map.containsKey(num) || map.get(num) ==0){
				map.put(num, 1);
			} else{
				map.put(num, map.get(num)+1);
				if(map.get(num) ==2){
					result += 1;
					map.put(num, 0);
				}
			}
		}
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		bw.write(String.valueOf(result));
		bw.flush();
		bw.close();
		br.close();
		}
}