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: Accepted)

fun main(args: Array<String>) {

    val N = readLine()!!.toInt()
    val Z = readLine()!!

    val A = 'A'
    val B = 'B'
    val C = 'C'

    var i = 0
    var answer = 0

    if(N < 3){
        println("0")
        return
    }

    while(true){
        if(Z[i] == A && Z[i+1] == B && Z[i+2] == C){
            answer++
            i+=3
        }else{
            i++
        }
        if(i >= N-2)break
    }

    println(answer)
}