import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = Integer.parseInt(sc.nextLine());
		String line = sc.nextLine();
		sc.close();
		int con = 0;
		for (int i = 0; i < len - 2; i++) {
			String cut = line.substring(i, i + 3);
			if (cut.equals("ABC")) {
				con++;
			}
		}

		System.out.println(con);

	}
}

/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