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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>) {
    val N = readLine()!!.toInt()
    val S = readLine()!!

    var count = 0
    var current = 0
    a@ for (s in S) {
        when (current) {
            0 -> {
                if (s == 'A') current++ else current = 0
                continue@a
            }
            1 -> {
                if (s == 'B') current++ else current = 0
                continue@a
            }
            2 -> if (s == 'C') {
                count++
                current = 0
                continue@a
            }
        }
    }
    println(count)
}