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)

function Main(input) {
  var nums = input.split('\n');

  var num = Math.floor(nums[0]);
  var str = nums[1];
  
  var ans = 0;
  
  for (var i = 0; i < num - 2; i++) {
    if (str[i] === 'A') {
      if (str[i + 1] === 'B') {
        if (str[i + 2] === 'C') {
          ans++;
        }
      }
    }
  }
  
  console.log(ans);
}
Main(require('fs').readFileSync('/dev/stdin', 'utf8'));