import java.util.Scanner;

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

        boolean isFound = false;
        int aLocation = 0;
        int zLocation = 0;
        for(int i=0; i<s.length; i++) {
            if(s[i] == 'A' && !isFound) {
                isFound = true;
                aLocation = i;
            } else if(s[i] == 'Z') {
                zLocation = i;
            }
        }
        System.out.println(zLocation - aLocation + 1);
        sc.close();
    }
}

/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