题解 | #丢失的三个数#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        boolean[] fs = new boolean[10001];
        for(int i = 0; i < 9997; i++) {
            fs[sc.nextInt()] = true;
        }
        String ans = "";
        for(int i = 1; i < 10001; i++) {
            if(!fs[i]) {
                ans += i;
            }
        }
        System.out.println(Long.parseLong(ans) % 7);
    }
}