import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {
		OriginScanner os = new OriginScanner();
		PrintWriter pw = new PrintWriter(System.out);
		
		int n = os.nextInt();
		String s = os.next();
		
		int count = 0;
		while (s.contains("ABC")) {
			s = s.replaceFirst("ABC", "");
			count++;
		}
		pw.println(count);
		pw.close();
	}
	
	static class OriginScanner {
		private BufferedReader br;
		private StringTokenizer st;
		
		public OriginScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}
		String nextLine() {
			String str = null;
			try {
				str = br.readLine();
			}
			catch (IOException e) {
				System.out.println(e);
			}
			return str;
		}
		String next() {
			if (st == null || !st.hasMoreTokens()) {
				st = new StringTokenizer(nextLine());
			}
			return st.nextToken();
		}
		int nextInt() {
			return Integer.parseInt(next());
		}
		long nextLong() {
			return Long.parseLong(next());
		}
	}
}
/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