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 JavaScript (Node.js 12.16.1) (judge verdict: Accepted)

"use strict";

function main(input) {
  input = input.trim().split("\n");
  const N = parseInt(input[0]);
  const S_arr = input[1].split("");
  let ans = 0;
  for (let i = 0; i < N; i++) {
    if (S_arr[i] === "A") {
      if (S_arr[i + 1] === "B") {
        if (S_arr[i + 2] === "C") {
          ans++;
        }
      }
    }
  }
  console.log(ans);
}

main(require("fs").readFileSync("/dev/stdin", "utf-8"));