Recursive Methods ; StringIndexOutOfBoundsException

This is a code to count how many times a character appeared in a String...
It has to be done recursively...

Code :

---

import java.io.*;
public class Methods{
	public static void main(String args []) throws IOException{
		InputStreamReader instream = new InputStreamReader(System.in);
		BufferedReader br = new BufferedReader (instream);
		System.out.println("Please insert a passage");
		String passage = br.readLine();
		System.out.println("Please insert character");
		String crc = br.readLine();
		char x = crc.charAt(0);
		System.out.println("This passage has this character " + crccount(passage, x)); 
	}
	public static int crccount(String passage, char x){
		int count = 0;
		int z = passage.length();
		if (z == 0){
			return 0;
		}
		if (passage.charAt(z) == x){
			count++;
		}
		return count + crccount(passage.substring(0, z-1), x);
	}
}

---

RUNTIME:
Please insert a passage
medo
Please insert character
e
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4
at java.lang.String.charAt(String.java:686)
at Methods.crccount(Methods.java:459)
at Methods.main(Methods.java:451)


Any suggestions?

change only 1 line

Code Java:

---

 
package test;
 
import java.io.*;
public class Methods{
	public static void main(String args []) throws IOException{
		InputStreamReader instream = new InputStreamReader(System.in);
		BufferedReader br = new BufferedReader (instream);
		System.out.println("Please insert a passage");
		String passage = br.readLine();
		System.out.println("Please insert character");
		String crc = br.readLine();
		char x = crc.charAt(0);
		System.out.println("This passage has this character " + crccount(passage, x)); 
	}
	public static int crccount(String passage, char x){
		int count = 0;
		int z = passage.length();
		if (z == 0){
			return 0;
		}
                else if (passage.charAt(z-1) == x){//just change this line 
			count++;
		}
		return count + crccount(passage.substring(0, z-1), x);
	}
}

---

I hope it will work

THANKS ALOT MAN...
I HONESTLY APPRECIATE IT... :D

I didn't notice charAt method starts at 0... Silly mistakes :@
Thanks alot though ;)