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 a = S.length();
			
			S = S.replaceAll("ABC", "");
			
			int b = S.length();
			
			int c = (a - b) / 3 ;
			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