import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    /**
     * A to Z String
     * @param 1 ≦ |s| ≦ 200,000
     */
    public static void main(String...args) {
        try (Scanner sc = new Scanner(System.in)) {
            String s = sc.next();
            String array[] = s.split("");
            int a = -1;
            int z = 0;
            for (int i = 0; i < array.length; i++) {
                if (a < 0) {
                    if (array[i].equals("A")) {
                        a = i;
                    }
                } else {
                    if (array[i].equals("Z")) {
                        z = i;
                    }
                }
            }
            System.out.println(z - a + 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