import java.util.*;

public class Main
{
    public static void main(String... args){
        Scanner sc= new Scanner(System.in);
        String s = sc.next();
        int first = -1;
        int last = -1;
        for (int i = 0; i < s.length(); i++) {
            int c = s.charAt(i);
            if (c == 'A' && first == -1){
                first = i;
            } else if (c == 'Z'){
                last = i;
            }
        }
        System.out.println(last - first + 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