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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>

using namespace std;

int main(){
	int N;
	cin >> N;
	char* S = (char*)calloc(N+1, sizeof(char));
	for(int i = 0; i < N; i++){
		cin >> S[i];
	}
	
	int count = 0;
	for(int i = 0; i < N-2; i++){
		if(S[i] == 'A'){
			if(S[i+1] == 'B'){
				if(S[i+2] == 'C'){
					count++;
				}
			}
		}
	}
	cout << count << endl;
	
}