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: Accepted)

import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Stream;

public class Main {

  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    final int n = scanner.nextInt();
    final String s = scanner.next();
    final String s1 = s.replaceAll("ABC", "a");
    List<String> sl = Arrays.asList(s1.split(""));
    System.out.println(sl.stream()
        .filter(e -> e.equals("a"))
        .count());
  }
}