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 c=0;

   for(int b=0;b<n-2;b++){
 	if(s.substring(b,b+1).equals("A")&&s.substring(b+1,b+2).equals("B")&&s.substring(b+2,b+3).equals("C")){
    		c++;
   	 }

        }
    	System.out.println(c);
    }
}
/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