import java.util.Scanner;
public class Main{
	String s;

	public Main(String str){
		s = str;
	}
	public int searchA(){
		return s.indexOf("A");
	}
	public int searchZ(){
		return s.lastIndexOf("Z") + 1;
	}

	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		String str = scan.nextLine();
		Main m = new Main(str);
		int start = m.searchA();
		int end = m.searchZ();
		System.out.println(end - start);

	}
}


/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