import java.util.*;

class Main {
	public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	String s = sc.next();
	int a = 0;
	int z = 0;
	for(int i=0; i<s.length();i++) {
		if(s.charAt(i) == 'A') {
			a = i;
			break;
		}
	}
	for(int j=1; j<=s.length(); j++) {
		if(s.charAt(s.length() - j) == 'Z') {
			z = s.length() - j;
			break;
		}
	}
	System.out.println(z-a+1);
	}
}
/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