public class SockMerchant {
    // https://www.hackerrank.com/challenges/sock-merchant/problem

    public SockMerchant() {
        boolean[] booleanArray = new boolean[101];
        int count = 0;

        Scanner in = new Scanner(System.in);
        int n = in.nextInt();

        for(int i = 0; i < n; i++){
            int color = in.nextInt();

            if (booleanArray[color]) {
                count++;
                booleanArray[color] = false;
            } else {
                booleanArray[color] = true;
            }
        }

        System.out.println(count);
    }
}