import java.util.*;

public class Main {

  public static void main (String[] args) {

    Scanner sc = new Scanner(System.in);

    String S_ = sc.next();

    sc.close();

    String[] S = S_.split("");

    int start = 0;
    
    for (int i = 0; i < S.length; i++) {

      if (S[i].equals("A")) {
        start = i;
        break;
      }

    }

    int end = 0;

    for (int i = S.length - 1; 0 <= i; i--) {

      if (S[i].equals("Z")) {
        end = i;
        break;
      }

    }

    System.out.println(end - start + 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