import java.util.Scanner;
 
public class Main {
	static Scanner in = new Scanner(System.in);
 
	public static void main(String[] args) {
		String s = in.next();
		int S = 0, E = 0;
		for(int i = 0; i < s.length(); i++){
			if(s.charAt(i) == 'A'){
				S = i;
				break;
			}
		}
		for(int i = s.length() - 1; i > -1; i--){
			if(s.charAt(i) == 'Z'){
				E = i;
				break;
			}
		}
		System.out.println(E - S + 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