import java.util.Arrays;

class Solution {
    public int solution(int n, int[] lost, int[] reserve) {
        Arrays.sort(lost);
        Arrays.sort(reserve);

        int lostLength = lost.length;
        int borrowCnt = 0;

        // 도둑 맞은 학생 중 본인 여벌은 본인이 챙기기
        int jIdx = 0;
        for (int i = 0; i < lostLength; i++) {
            int lostNo = lost[i];

            for (int j = jIdx; j < reserve.length; j++) {
                if (lostNo == reserve[j]) {
                    borrowCnt++;
                    reserve[j] = -1;
                    lost[i] = -1;
                    jIdx++;
                    break;
                }
            }
        }

        // 도둑 맞은 학생 중 앞 뒤 학생에게 여벌 빌리기
        jIdx = 0;
        for (int i = 0; i < lostLength; i++) {
            int lostNo = lost[i];

            if (lostNo < 0) continue;

            for (int j = jIdx; j < reserve.length; j++) {
                int reserveNo = reserve[j];

                if (reserveNo == lostNo - 1 || reserveNo == lostNo + 1) {
                    borrowCnt++;
                    reserve[j] = -1;
                    jIdx++;
                    break;
                }
            }
        }

        return n - lostLength + borrowCnt;
    }
}