

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String str = sc.next();

		int indexA = 0;
		while(str.charAt(indexA) != 'A'){
			indexA++;
		}
		int indexB = str.length();
		while(str.charAt(indexB - 1) != 'Z'){
			indexB--;
		}

		System.out.println(indexB - indexA);
    }
}
/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