3 пункт
package com.javarush.task.task18.task1803;
import java.io.*;
import java.util.*;
/*
Самые частые байты
*/
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
String s = reader.readLine();
FileInputStream r = new FileInputStream(s);
List<Integer> list = new ArrayList<>();
Map<Integer, Integer> max_list = new HashMap<>();
while (r.available() > 0) {
list.add(r.read());
}
for (int i = 0; i < list.size(); i++) {
int count = 0;
for (int j = i + 1; j < list.size(); j++) {
if(list.get(i) == list.get(j)) {
count++;
list.remove(j);
j--;
}
}
max_list.put(count, list.get(i));
}
int q = 0;
for(Map.Entry<Integer, Integer> entry : max_list.entrySet()) {
if(q < entry.getKey()) {
q = entry.getKey();
}
}
for(Map.Entry<Integer, Integer> entry : max_list.entrySet()) {
if(q == entry.getKey()) {
System.out.print(entry.getValue() + " ");
}
}
r.close();
}
}