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<iostream>
#include<vector>
#include<set>
#include<unordered_set>
#include<list>
#include<stack>
#include<queue>
#include<map>
#include<unordered_map>
#include<algorithm>
#include<cmath>
#include<tuple>
#include<iomanip>
#include<climits>
#define ll long long int
#define mod 1000000007
#define pi acos(-1)
using namespace std;

int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  string str;
  cin>>n>>str;
  int count=0;
  for(int i=0;i<n-2;i++)
  {
    if(str.substr(i,3)=="ABC")
      count++;
  }
  cout<<count<<endl;
  return 0;
}