import java.util.*;

//atcoderはScannerクラスのsc.next()で行ける
public class Main{
    public static void main (String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        String S = sc.next();
        String ABC = "ABC";
        int cnt = 0;
        // abcabcabc
        for (int i = 0; i < n-2 ; i++){
            if(S.substring(i,i+3).equals(ABC)){
                cnt++;
            }
        }
        System.out.println(cnt);
    }
}
/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