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 ll long long 
#define pi  pair<int,int>
#define ti  tuple<int,int,int>
#define mt  make_tuple
#define mk  make_pair
#define vi  vector<int>
#define vll vector<ll>
#define fastInOut ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pr(a) for(auto x:a) cout<<x<<" ";
#define prmap(m) for(auto x:m) cout<<x.first<<" "<<x.second<<"\n";


ll n,m;
int main() {
    fastInOut
    ll k,x;

    cin>>k;
    string s;
    cin>>s;
    int c=0;
    for(int i=0;i<k;i++){
     if(s[i]=='A'&&s[i+1]=='B'&&s[i+2]=='C'){
         c++;
         i++;
      }
    }
     cout<<c;

  return 0;
}