import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    String s = sc.next();
    int answer =0;
    for(int i =0;i<s.length()-2;i++){
      if(s.substring(i,i+1).equals("A")&&s.substring(i+1,i+2).equals("B")&&s.substring(i+2,i+3).equals("C")){
                 answer=answer+1;
      }
    }
    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