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;
typedef long long ll;
const int N=1e2+5;

#define endl '\n'

char str[N];

int main(){
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	int n,cnt=0;
	cin>>n>>str;
	for(int i=0;i<n;i++){
		if(str[i]=='A'){
			if(str[i+1]=='B'){
				if(str[i+2]=='C'){
					cnt++;
					i+=2;
				}
			}
		}
	}
	cout<<cnt<<endl;
	return 0;
}