import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int val1 = sc.nextInt();
        String val2 = sc.next();

        int count = 0;
        String temp = "";
        for (int i = 0; i < val2.length(); i++) {
            temp = temp + val2.charAt(i);
            switch (temp) {
                case "A":
                    continue;
                case "AB":
                    continue;
                case "ABC":
                    count++;
                    temp = "";
                    continue;
                default:
                    temp = "" + temp.charAt(temp.length() - 1);

            }
        }
        System.out.println(count);
    }
}
/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