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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<stdio.h>
#include<map>
#include<queue>
#include<vector>
using namespace std;

typedef long long ll;

int main(){
	int n,ans=0;
	char s[55];
	cin>>n;
	for(int i=0;i<n;i++) cin>>s[i];
	for(int i=0;i<n-3;){
		if(s[i]=='A'&&s[i+1]=='B'&&s[i+2]=='C'){
			i+=3;
			ans++;
		}else{
			i++;
		}
	}
	cout<<ans;
	return 0;
}