import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		String s = stdIn.next();
		char[] words = s.toCharArray();
		int min = 0;
		int max = 0;
		for(int i = s.length()-1; i >= 0; i--) {
			if(words[i] == 'A') {
				min = i;
			}
		}
		for(int i = 0; i < s.length(); i++) {
			if(words[i] == 'Z') {
				max = i;
			}
		}
		System.out.println(max-min+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