import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    String S = sc.next();
	int ans = 0;
    for (int i=0;(i+3) <= N;i++){
//      System.out.println("i" + i);
//      System.out.println(S.substring(i,(i+3)));
      if(S.substring(i,(i+3)).equals("ABC")){
        ans++;
      }
    }
    System.out.println(ans);
  }
}
/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