import java.util.Scanner;

public class Main {

	private static final String ABC = "ABC";

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

		int n = sc.nextInt();
		String s = sc.next();
		sc.close();

		int count = 0;
		int it = 0;
		int result = 0;
		while (result != -1) {
			result = s.indexOf(ABC, it);
			if (result != -1) {
				count++;
				it = result + ABC.length();
			}
		}

		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