题目来源:PAT 乙级真题——1028 人口普查 (20 分)
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
public static void main(String[] args) throws IOException {
//Scanner sc = new Scanner(System.in);
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.valueOf(br.readLine());
int count = 0; // 记录有效生日的个数
int max = Integer