import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
      	String str = sc.next();
      	Integer cnt = 0;
      	Integer flag = 0;
		for(int i=0; i < N; i++){
          if(str.charAt(i)=='A'){
          	if((i+1!=N)&&(str.charAt(i+1)=='B')){
              if((i+2!=N)&&(str.charAt(i+2)=='C')){
                cnt++;
              }
          	}
          }
        }
		System.out.println(cnt);
      	return;
	}
}

/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