

import java.util.Scanner;

class Main{
	public static void main(String[] ag) {
		Scanner sc=new Scanner(System.in);
		String a=sc.next();

		int st=0;
		int gl=a.length()-1;


		for(int i=0; i<a.length(); i++) {
			if(a.charAt(i)=='A') {
				st=i+1;
				break;
			}
		}

		for(int i=a.length()-1; i>=0; i--) {
			if(a.charAt(i)=='Z') {
				gl=i+1;
				break;
			}
		}
		System.out.println(gl-st+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