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 mp make_pair
#define pb push_back
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,n,s) for(int i=(s);i<(n);i++)
typedef long long int ll;
using namespace std;
using Graph = vector<vector<int> >;

int main(){
cin.tie(0);
ios::sync_with_stdio(false);
int N;
string S;
cin>>N>>S;
int cnt=0;
rep(i,N-2){
    if(S.substr(i,3)=="ABC"){
        cnt++;
    }
}
cout<<cnt<<endl;
//system("pause");
return 0;
}