import java.util.Scanner;

public class Main{

   public static void main(String[] args){
      
      Scanner reader = new Scanner(System.in);
      
      String s = reader.next();
      int iA = -1;
      int iZ = 0;
      
      for(int i = 0; i < s.length(); i++){
         String l = s.substring(i, i+1);
         if(l.equals("A") && iA < 0){
            iA = i;
         } else if(l.equals("Z") && i > iZ){
            iZ = i;
         }
      }
      
      System.out.println(iZ - iA + 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