import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String S = sc.next();
		int firstIndex = S.length();
		int lastIndex = S.length();
		char[] sArray = S.toCharArray();
		for (int i = 0; i < sArray.length; i++) {
			if (sArray[i] == 'A') {
				firstIndex = i;
				break;
			}
		}
		for (int i = 0; i < sArray.length; i++) {
			if (sArray[i] == 'Z')
				lastIndex = i;
		}
		System.out.println(S.substring(firstIndex, lastIndex + 1).length());
		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