import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int i = 0;
        int o = 0;
        String sub = "ABC";
        int n = sc.nextInt();
        String s = sc.next();

            while ((i = s.indexOf(sub, i)) != -1) {
                o++;
                i++;
            }


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