import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner s = new Scanner(System.in);
    String U = s.next();
    int a = 0;
    int b = U.length() - 1;
    while (U.charAt(a) != 'A'){
      a++;
    }
    while (U.charAt(b) != 'Z'){
      b--;
    }
    System.out.println(b - a + 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