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 (1.3.71) (judge verdict: Wrong Answer)

fun main (args:Array<String>){
    var strLen = readLine()!!.toInt()
    var strS = readLine()!!
    var count = 0

    while(strLen > 3){
        var abcIndex = strS.indexOf("ABC")
        if(abcIndex == -1){
            return
        }
        else {
            strS = strS.drop((abcIndex + 3))
            count++
            strLen -= abcIndex + 3
        }
    }
    print(count)
}