import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        boolean started = false;
        int len = 0;
        int index1 = 0, index2;
        for (int i=0; i<a.length(); i++) {
            if (!started && a.charAt(i) == 'A') {
                started = true;
                index1 = i;
            }
            if (started && a.charAt(i) == 'Z') {
                started = true;
                index2 = i;
                len = index2 - index1 + 1;
            }
        }
        System.out.println(len);
    }
}

/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