Integer.parseInt() throws NumberFormatException for some numbers read using BufferedReader from one file but not another

I am trying to read numbers from a text file.

The first lines of metro.txt contain:

376 9330000 Abbesses0001 Alexandre Dumas

Whereas the first few lines of testnum.txt contain:

444 5556666 flowers8888 pumpkin patch

This is my code:

import java.io.BufferedReader;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.IOException;public class test {    public static void main(String[] args) {        try {            FileReader input = new FileReader("metro.txt");            BufferedReader reader = new BufferedReader(input);            String raw_line = reader.readLine();            String[] split_line = raw_line.split(" ", 2);            int num_vertices = Integer.parseInt(split_line[0]);            int num_edges = Integer.parseInt(split_line[1]);        } catch (FileNotFoundException ex) { // catch filereader            System.out.println(ex);        } catch (IOException ex) { // catch bufferedreader            System.out.println(ex);        }    }}

When I run it with "metro.txt" in the filereader arg, I get the error:

Exception in thread "main" java.lang.NumberFormatException: For input string: "376"        at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)        at java.base/java.lang.Integer.parseInt(Integer.java:668)        at java.base/java.lang.Integer.parseInt(Integer.java:786)        at test.main(test.java:15)

Whereas when I run it with "testnum.txt" I get no such error. I was provided "metro.txt" as part of an assignment and created "testnum.txt" myself and can only think of some sort of encoding of the text is causing this.

I think its something to do with how the bufferedreader is reading from "metro.txt" as when I try and compare split_line[0] with an identical string "376" it returns false but I have no idea how to get to the root of this issue.