import java.io.IOException;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		Scanner scanner = new Scanner(System.in);
		String str = scanner.nextLine();
		if(str.indexOf("A") != -1 && str.lastIndexOf("Z") != -1){
			System.out.println((str.substring((str.indexOf("A")),str.lastIndexOf("Z")+1)).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