import java.util.*;
import java.util.stream.Collectors;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		
		int indexOfA = s.indexOf('A');
		int indexOfZ = s.lastIndexOf('Z');
		String subst = s.substring(indexOfA, indexOfZ+1);
		int ans = subst.length();
		System.out.println(ans);
		sc.close();
	}
}
/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