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;
      A = S.indexOf("A");
      Z = S.lastIndexOf("Z");
      System.out.println(Z-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