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

public class Main {
	public static void main(String[] args) throws IOException{
	Scanner sc= new Scanner(System.in);
	
	String str = sc.next();
	String line = str.substring(str.indexOf("A"), str.lastIndexOf("Z"));
	System.out.println(line.length()+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