import static java.lang.System.*;
import java.util.Scanner;

public class Main{
	
	public static void main(String[] args) {
		Scanner s = new Scanner(in);
		
		String input = s.nextLine();
		
		int res = input.lastIndexOf("Z") - input.indexOf("A") + 1;
		
		out.println(res);
	}
}
/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