import java.util.*;
import java.io.*;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		String s = in.nextLine();
		
		
		int start = -1;
		int end = -1;
		for(int i = 0; i < s.length(); i++){
			if(s.charAt(i) == 'A' && start == -1){
				start = i;
			}
			if(s.charAt(i) == 'Z' && start != -1){
				end = i;
			}
		}
		System.out.println(end-start+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