import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        int startA = 0;
        boolean isA = false;
        int endZ = 0;
        for (int i=0; i<s.length();i++) {
            if (!isA && "A".equals(s.substring(i,i+1))) {
                startA = i;
                isA = true;
            } else if ("Z".equals(s.substring(i,i+1))) {
                endZ = i;
            }
        }
        System.out.println(endZ - startA +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