import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] s = sc.next().split("");
		int count = 0;

		for(int i = 0;i < n-2;i++) {
			if(s[i].equals("A")) {
				if(s[i].concat(s[i+1]).concat(s[i+2]).equals("ABC")) {
					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