import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();
		String s = sc.next();
		int count = 0;
		String s1 = s.replace("ABC", "");
		int diff = s.length()-s1.length();
		System.out.println(diff/3);
	}

}
/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