import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String word = input.nextLine();
        int n = word.length();
        int maximumLength = 0;
        boolean end = false;
        for (int i = 0; i < n; i++) {
            if(word.charAt(i) == 'A')
            {
                for (int j = i+1; j < n; j++) {
                    if(word.charAt(j) == 'Z')
                    {

                        if(j-i+1 > maximumLength)
                        {
                            maximumLength = j - i + 1;
                        }
                    }

                    if(j == n-1)
                        end = true;

                }
            }
            if(end)
                break;
        }
        System.out.println(maximumLength);
        }
}
/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