
import java.util.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		String s=sc.nextLine();
		int i=0;
		while(s.charAt(i)!='A')
		{
			i++;
		}
		int j=s.length()-1;
		while(s.charAt(j)!='Z')
		{
			j--;
		}
		System.out.println(s.substring(i,j+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