import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.*;

public class Main {
  public static void main(String[] args) throws IOException {
		Scanner scn = new Scanner(System.in);
		int n = scn.nextInt();
		String s = scn.next();
		String x = "ABC";
		int ans = 0;
		for (int i = 0; i + 3 <= n; i++) {
			if (s.substring(i, i + 3).equals(x))
				ans++;
		}
		System.out.println(ans);
  }
}
/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