First of all just read First line of the file.
File f=new File("your_file.txt");
FileReader fr=new FileReader(f);
BufferedReader br=new BufferedReader(fr);
String firstLine=br.readLine();
Then split the line by spaces to get String array of words
String[] words=firstLine.split("\\s+");
Split the fourth word using " . "
String[] nos=words[3].split("\\.");
System.out.println(nos[0]);//Expected output, First number of fourth
//word in first line of given file