
import java.io.InputStream;
import java.io.PrintStream;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        solve(System.in, System.out);
    }

    static void solve(InputStream is, PrintStream os) {
        // Your code here!
        Scanner scan = new Scanner(is);
        int N = scan.nextInt();
        String S = scan.next();

        int state = 0;
        int ans = 0;
        for(int i = 0; i < S.length(); i++){
            switch (state) {
                case 0: {
                    if (S.charAt(i) == 'A')
                        state = 1;
                    break;
                }

                case 1: {
                    if (S.charAt(i) == 'A')
                        state = 1;
                    else if (S.charAt(i) == 'B')
                        state = 2;
                    else
                        state = 0;
                    break;
                }

                case 2: {
                    if (S.charAt(i) == 'C') {
                        ans++;
                        state = 0;
                    }
                    else if(S.charAt(i) == 'A')
                        state = 1;
                    else
                        state = 0;
                    break;
                }
            }
        }

        os.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