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: Runtime Error)

//どうかACをお恵みくださいお願いしますお願いしますお願います何もしませんから
using System;

namespace AtCoder
{
    class Program
    {
        static void Main()
        {
            int N = int.Parse(Console.ReadLine());
            string S = Console.ReadLine();
            int g = 0;
            for(int x = 0;x < N-2;x++)
            {
                if(S.Substring(x,x+2)=="ABC")
                {
                    g = g + 1;
                }
            }
            Console.WriteLine(g);
        }
    }
}