import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       int N = scan.nextInt();
       int count = 0;
       String m = "A";
       String str = scan.next();
       for(int i = 0;i<N-2;i++){
           if(str.substring(i,i+3).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