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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

int main(){
  int n, c = 0;
  bool a = 0, b = 0;
  string s;
  cin >> n >> s;
  for(int i = 0; i < n; ++i){
    if(a && b){
      if(s[i] == 'C') ++c;
      a = 0;
      b = 0;
    }
    else if(a){
      if(s[i] == 'B') b = 1;
      else a = 0;
    }
    else if(s[i] == 'A') a = 1;
    else{
      a = 0;
      b = 0;
    }
  }
  cout << c << endl;
}