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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		String str = scan.nextLine();
		str = scan.nextLine();
		scan.close();

		char[] c = str.toCharArray();
		int ans = 0;
		int flg = 0;
		for (int i=0; i < n; i++) {
			if (flg == 0 && c[i] == 'A') {
				flg =1;
			} else if (flg == 1 && c[i] == 'B') {
				flg =2;
			} else if (flg == 2 && c[i] == 'C') {
				ans +=1;
				flg = 0;
			} else {
				flg = 0;
			}
		}
		System.out.println(ans);
	}
}