import java.util.*;
public class Main{
public static void main(String[]args){
Scanner sc=new Scanner(System.in);
  String po=sc.nextLine();
  String[]s=po.split("");
  int i,j;
  for(i=0;true;i++){
  if(s[i].equals("A"))break;
  }
  
  for(j=s.length-1;true;j--){
  if(s[j].equals("Z"))break;
  }
  System.out.println(j-i+1);
}
}

/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