import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int charCount = sc.nextInt();
		String word = sc.next();
		int answer = 0;
		int index = 0;
		while(true) {
			index = word.indexOf("ABC");
			if(index == -1){
				break;
			}else {
				word = word.substring(index +3);
				answer++;
			}
		}
		System.out.println(answer);

	}
}
/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