import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
      int N = sc.nextInt(); // 合計値
      String S = sc.next();
      S = S.replaceAll("ABC", "");
      int diff = N - S.length();
      if(diff > 0){
      	System.out.println(diff / 3);
      } else {
        System.out.println(0);
      }
   }
}

/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