import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        String s = new Scanner(System.in).next();
        int b = s.indexOf('A');
        int e = s.lastIndexOf('Z');
        s = s.substring(b,e+1);
        System.out.println(s.length());
    }
}
/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