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: Wrong Answer)

using System;

namespace vscode
{
    class Program
    {
        static void Main(string[] args)
        {
            int length = int.Parse(Console.ReadLine());
            string testee = Console.ReadLine();

            int cntAbc = matchWords(testee.ToCharArray(), "ABC".ToCharArray(), length);

            Console.WriteLine(cntAbc);
        }

        static int matchWords(char[] testee, char[] matcher, int length) {
            if (length < 3 || length > 50) return 0;

            int found = 0;
            int pos=0;
            int vurpos=0;
            
            while(pos <= length-1) {
                if (testee[pos] == matcher[vurpos]) {
                    vurpos++;
                    if(vurpos == 3){
                        found++;
                        vurpos=0;
                    }

                } else {
                    vurpos=0;
                }

                pos++;
            }
            return found;
        }
    }
}