import java.util.Scanner;

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

        String s = sc.next();

        int min = 0;
        int max = 0;

        for (int i = 0; i < s.length(); i++) {
            if (min == 0 && s.charAt(i) == 'A')
                min = i+1;
            if (min > 0 && s.charAt(i) == 'Z')
                max = i+1;
        }

        int ans = max - min;
        System.out.println(ans+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