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

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = "";
		int strN = 1; // 文字列を何行受け取るか
		for (int i = 0; i < strN; i++) {
			line += br.readLine() + " ";
		}
		String[] param = line.split(" ");
		AZ(param);

	}

	static void AZ(String[] param) {

		System.out.println((param[0].lastIndexOf("Z")) - (param[0].indexOf("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