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;
#define endl "\n"
typedef long long int ll;

int main()
{

	ios_base:: sync_with_stdio(false); cin.tie(0);
	int n;
	cin>>n;
	string s;
	cin>>s;
	int cnt=0;

	for(int i=0; i+3<n; i++) {
		string a=s.substr(i,3);
		if(a=="ABC") {
			cnt++;
		}
	}
	cout<<cnt<<endl;
	return 0;
}