import java.util.Scanner;
import java.util.regex.*;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int count = 0;

		sc.next();
		String s = sc.next();
		Pattern p = Pattern.compile("ABC");
		Matcher m = p.matcher(s);

		while(m.find()) count++;

		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