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import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
class Main {
    private static final long TIMES = 1000000000;
    private static void help(Set<Long> set, long x, long y) {
        // System.out.println(x + ";" + y);
        long key = x * TIMES + y;
        if (set.contains(key))
            set.remove(key);
        else
            set.add(key);
    }
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        Set<Long> set = new HashSet<>();
        for (int i = 0; i < N; ++i) {
            long xi = scanner.nextInt();
            long yi = scanner.nextInt();
            help(set, xi, yi);
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