please help
package com.codegym.task.task19.task1907;
import java.io.*;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
/*
Counting words
*/
public class Solution {
public static final String regrex = "\\bworld\\b";
public static String input ;
public static void main(String[] args) throws IOException{
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String file_name = reader.readLine();
FileReader file_reader = new FileReader(file_name);
int count = 0;
Pattern pattern = Pattern.compile(regrex);
Matcher matcher ;
while(file_reader.ready()){
input += (char) file_reader.read();
}
matcher = pattern.matcher(input);
while(matcher.find()){
count++;
}
reader.close();
file_reader.close();
System.out.println(count);
}
}