I tested manually, it seems ok. Validation says: "Be sure that the program displays the maximum number."
package com.codegym.task.task05.task0532;
import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/*
Task about algorithms
*/
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String strLine = "";
int n=0;
List<Integer> num = new ArrayList<>();
for(int i = 0; i < 3; i++){
strLine = reader.readLine();
num.add(Integer.parseInt(strLine));
n++;
}
if(n > 0){
int maximum = Collections.max(num);
System.out.println(maximum);
}else{
}
}
}