import java.util.*;
 
public class Main{
	public static void main(String[] args){
	    Scanner sc = new Scanner(System.in);
    	String s = sc.next();
        int a = 0;
        int z = 0;
        for(int i = 0; i < s.length(); i++){
        	if(s.charAt(i) == 'A'){
            	a = i;
                break;
            }
        }
        for(int i = 0; i < s.length(); i++){
        	if(s.charAt(i) == 'Z'){
            	z = i + 1; 
            }
        }
        System.out.println(z - a);
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz