import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        String S = input.readLine();


        int APosition = 0;
        for (int i = 0; i < S.length(); i++) {
            if (isA(S.charAt(i))) {
                APosition = i;
                break;
            }
        }

        int ZPosition = S.length() - 1;
        for (int i = S.length() - 1; i >= 0; i--) {

            if (isZ(S.charAt(i))) {
                ZPosition = i;
                break;
            }
        }

        System.out.println(ZPosition-APosition+1);
    }

    private static boolean isA(char c) {
        return c == 'A';
    }

    private static boolean isZ(char c) {
        return c == 'Z';
    }
}
/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