import java.util.*;
 
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    String[] S = new String[s.length()];
    int a = -1;
    int length = 0;
    S = s.split("");
    for (int i = 0; i < s.length(); i++) {
      if (S[i].equals("A") && a == -1) {
        a = i;
      }
      if (S[i].equals("Z") && a != -1) {
        length = i - a + 1;
      }
    }
    System.out.println(length);
  }
}
    
/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