import java.util.Scanner;

public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);

		String s = scan.next();
		char[] c = s.toCharArray();

		int start = 0;
		for(int i = 0; i < s.length(); i++){
			if(c[i] == 'A'){
				start = i;
				break;
			}
		}

		int end = 0;
		for(int i = s.length()-1; i > start; i--){
			if(c[i] == 'Z'){
				end = i;
				break;
			}
		}
		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