import java.util.*;

public class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    
    int n = sc.nextInt();
    sc.nextLine();
    String s = sc.nextLine();
    int i = 0;
    int cnt = 0;
    
    do{
      i = s.indexOf("ABC", i);
      if(i != -1){
        cnt++;
        i++;
      }
    }while(i >= 0);
    
    System.out.println(cnt);
  }
}
/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