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 int long long
#define ld long double
#define endl '\n'
#define vi vector<int>
#define vvi vector<vi>
#define pii pair<int, int>
#define vpii vector<pii>
#define gr vector<vpii>
#define fi first
#define se second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define YES cout << "YES" << endl
#define NO cout << "NO" << endl
#define GAME_OVER return 0
#define MOD (int)(1E9 + 7)
using namespace std;
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    int n;
    string s;
    cin >> n >> s;
    int res = 0;
    for (int i = 0; i < n; i++)
        if (i + 2 < n && s[i] == 'A' && s[i + 1] == 'B' && s[i + 2] == 'C')
            res++;
    cout << res << endl;
    GAME_OVER;
}