import java.util.*;

public class Main{
  public static void main(String[]args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    int s = S.length();
    int a = -1, z = 0;
    for(int i = 0; i < s; i++){
      if(S.charAt(i) == 'A' && a == -1){
        a = i;
      }else if(S.charAt(i) == 'Z'){
        z = i;
      }
    }
    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