https://www.acmicpc.net/problem/1302
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
public class Main {
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
HashMap<String, Integer> map = new HashMap<>();
int num = Integer.parseInt(br.readLine());
String book;
int max = -1;
int bookCount;
// HashMap에 책과 책의 수의 값을 추가
for (int i=0; i< num; i++) {
book = br.readLine();
if (!map.containsKey(book))
bookCount = 1;
else
bookCount = map.get(book)+1;
map.put(book, bookCount);
if (max < bookCount)
max = bookCount;
}
// 가장 많은 수의 책들을 list에 추가
ArrayList<String> list = new ArrayList<>();
for (String s: map.keySet()) {
if (map.get(s)== max)
list.add(s);
}
// 사전순으로정렬
Collections.sort(list);
// 가장 처음 책을 출력
System.out.println(list.get(0));
}
}