import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
		// 文字列の入力
        List<String> list = new ArrayList<>();
		list.addAll(Arrays.asList(sc.next().split("")));
        int aIndex = list.indexOf("A");
        int zIndex = 0;
        for(int i = aIndex + 1; i < list.size(); i++) {
          if (list.get(i).equals("Z")) {
            zIndex = i;
          }
        }
    
		// 出力
		System.out.println(zIndex - aIndex + 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