import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
	
		Scanner sc = new Scanner(System.in);
		
		String s = sc.next();
		char []a = s.toCharArray();
		int mina = s.length();
		int maxz = 0;
		
		for(int i = 0; i < s.length(); i++) {
			if(a[i] == 'A') {
				mina = Math.min(mina, i);
			}
			if(a[i] == 'Z') {
				maxz = Math.max(maxz, i);
			}
		}
		System.out.println((maxz - mina) + 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