using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve(new ConsoleInput(Console.In, ' '));
        }

        public void Solve(ConsoleInput cin)
        {
            int length = cin.ReadInt;
            string input = cin.Read;
            int i = 2;
            int counter = 0;
            while (i < length) {
                switch (input[i]) {
                    case 'C':
                        if (input[i - 1] == 'B' && input[i - 2] == 'A') {
                            counter++;
                        }
                        i += 3;
                        continue;
                    case 'B':
                        i += 1;
                        continue;
                    case 'A':
                        i += 2;
                        continue;
                    default:
                        i += 3;
                        continue;
                }
            }

            WriteLine(counter);


        //var nk = Console.ReadLine().Split(' ');
        //var n = int.Parse(nk[0]);
        //var k = int.Parse(nk[1]);

        //var t = new int[n][];
        //for (int i =0; i < n;i++) {
        //    t[i] = cin.ReadIntArray(n);
        //}

        //int n = cin.ReadInt;
        //int K = cin.ReadInt;

        //int[] array = new int[n];

        //for (int i =0; i < n; i++) {
        //    array[i] = cin.ReadInt;
        //}

        //for (int i =0; i < n; i++) {
        //    if (array[i] == 0) {
        //        WriteLine(n);
        //    }
        //}

        //int res = 0;
        //int right = 0;
        //long mult = 1;

        //for (int left = 0; left < n; left++) {
        //    while (right < n && mult * array[right] <= K) {
        //        mult *= array[right];
        //        right++;
        //    }

        //    res = Math.Max(res, right - left);
        //    if (left == right) right++;
        //    else mult /= array[left];


        //}
        //WriteLine(res);
    }
    }

    public class ConsoleInput
    {
        private readonly System.IO.TextReader _stream;
        private char _separator = ' ';
        private Queue<string> inputStream;
        public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
        {
            this._separator = separator;
            this._stream = stream;
            inputStream = new Queue<string>();
        }
        public string Read
        {
            get
            {
                if (inputStream.Count != 0) return inputStream.Dequeue();
                string[] tmp = _stream.ReadLine().Split(_separator);
                for (int i = 0; i < tmp.Length; ++i)
                    inputStream.Enqueue(tmp[i]);
                return inputStream.Dequeue();
            }
        }
        public string ReadLine { get { return _stream.ReadLine(); } }
        public int ReadInt { get { return int.Parse(Read); } }
        public long ReadLong { get { return long.Parse(Read); } }
        public double ReadDouble { get { return double.Parse(Read); } }
        public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
        public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
        public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
    }
}

Measured memory_bytes: 27908