import java.lang.Math;
import java.util.HashMap;
import java.util.Map;

public class HelloWorld {
    public static void main(String[] args) {

        System.out.println("After clear operation, size: " + calculateCharacters("Hello there! Apple!"));
    }

    private static Map<Character, Integer> calculateCharacters(String str) {
        Map<Character, Integer> characterCounter = new HashMap<>();

        for (int i = 0; i < str.toCharArray().length; ++i) {
            char charAt = str.charAt(i);

            if (charAt > 64 && charAt < 91 || charAt > 96 && charAt < 123) {
                if (!characterCounter.containsKey(charAt)) {
                    characterCounter.put(charAt, 1);
                } else {
                    characterCounter.put(charAt, characterCounter.get(charAt) + 1);
                }
            }
        }

        return characterCounter;
    }
}