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

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

		String aou = vf.readLine();

		int f = aou.indexOf("A");

		StringBuffer sb = new StringBuffer(aou);
		StringBuffer eou = sb.reverse();

		int e = eou.indexOf("Z");

		int o = aou.length() - f - e;

		System.out.println(o);

	}

}

/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