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: Accepted)

#include "bits/stdc++.h"
using namespace std;
#define db(x) cerr<<__LINE__<<": "<<#x<<" = "<<(x)<<'\n'
const int N = 1e6;

int main() {
	ios_base::sync_with_stdio(0);
	int a,b,n,T,cas=0;
	string s;
	cin>>n>>s;
	int cnt=0;
	for(int i=2;i<n;++i) {
		if(s[i-2]=='A' && s[i-1]=='B' && s[i]=='C') cnt++;
	}
	cout<<cnt;
	return 0;
}