import java.io.*;
 
public class CountString {
 
 public static int count(String filename, String target)
    throws FileNotFoundException, IOException {
   FileReader fr = new FileReader(filename);
   BufferedReader br = new BufferedReader(fr);
   StringBuilder strb = new StringBuilder();
   while (true) {
    String line = br.readLine();
    if (line == null) {
     break;
    }
    strb.append(line);
   }
   String result = strb.toString();
   int count = 0;
   int index = 0;
   while (true) {
    index = result.indexOf(target, index + 1);
    if (index > 0) {
     count++;
    } else {
     break;
    }
   }
   br.close();
   return count;
  }
 
 public static void main(String[] args) {
   try {
    System.out.println(count("D:\\zhang.txt", "a"));
   } catch (FileNotFoundException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
 
}