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>

#define ff first
#define ss second
#define pb push_back

using namespace std;
using ll = long long;
using ii = pair<int, int>;

const int N = 100005;

int main(){
	int n;
	char s[N];
	scanf("%d", &n);
	scanf("%s", s);
	int ans = 0;
	for(int i = 0; i < n-2; i++){
		if(s[i] == 'A' && s[i+1] == 'B' && s[i+2] == 'C'){
			ans++;
		}
	}
	printf("%d\n", ans);
	return 0;
}