public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int K = scan.nextInt();
    ArrayList<Integer> contest = new ArrayList<>(N);
    int savedLuck = 0;
    for (int i = 0; i < N; i++) {
        int luck = scan.nextInt();
        int importance = scan.nextInt();
        if (importance == 0) {
            savedLuck += luck; // lose every non-important contest
        } else {
            contest.add(luck);
        }
    }
    scan.close();
        
    /* Compete in "important" contests */
    quickselect(contest, 0, contest.size() - 1, contest.size() - K);
    for (int i = 0; i < contest.size(); i++) {
        if (i < contest.size() - K) {
            savedLuck -= contest.get(i); // win contest
        } else {
            savedLuck += contest.get(i); // lose contest
        }
    }
    System.out.println(savedLuck);
}