Problem:
Score : 200 points

Problem Statement

We have a string S of length N consisting of uppercase English letters.

How many times does ABC occur in S as contiguous subsequences (see Sample Inputs and Outputs)?

Constraints

3 \leq N \leq 50

S consists of uppercase English letters.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print number of occurrences of ABC in S as contiguous subsequences.

Sample Input 1

10
ZABCDBABCQ

Sample Output 1

2

Two contiguous subsequences of S are equal to ABC: the 2-nd through 4-th characters, and the 7-th through 9-th characters.

Sample Input 2

19
THREEONEFOURONEFIVE

Sample Output 2

0

No contiguous subsequences of S are equal to ABC.

Sample Input 3

33
ABCCABCBABCCABACBCBBABCBCBCBCABCB

Sample Output 3

5

Solution in C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;

class Program
{
    static void Main(string[] args)
    {
        Console.ReadLine();
        char[] s = Console.ReadLine().ToCharArray();
        int count = 0;
        for(int i = 0; i < s.Length - 2; i++)
        {
            if (s[i] != 'A')
                continue;
            if (s[i + 1] != 'B')
                continue;
            if (s[i + 2] == 'C')
                count++;
        }

        Console.WriteLine(count);

    }


}