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 v5.12) (judge verdict: Accepted)

'use strict';
const main = input => {
  const n = parseInt(input[0]);
  let s = input[1];
  let ans = 0;
  for(let i=0; i<s.length-2; i++) {
    if (s[i] == 'A' && s[i+1] == 'B' && s[i+2] == 'C') {
      ans++;
    }
  }
  console.log(ans);
  
}
main(require("fs").readFileSync("/dev/stdin", "utf8").split('\n'));