import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String s = scan.next();
		int s_length = s.length(); 
		int i = 0;
		int j = 0;
		for(i = 0; i < s_length; i++) {
			if(s.charAt(i) == 'A') {
				break;
			}
		}
		for(j = s_length - 1; j >= 0; j--) {
			if(s.charAt(j) == 'Z') {
				break;
			}
		}
		String str = s.substring(i, j + 1);
		System.out.println(str.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