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<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<queue>

using namespace std;

using ll=long long;
using vi=vector<int>;
using vvi=vector<vi>;
using pii=pair<int,int>;
using vll=vector<ll>;
using vvll=vector<vll>;
using vpii=vector<pii>;

#define PI 3.1415926535897932384626433832795

int main(void)
{
	int n;
	char s[50+2];
	while(scanf("%d\n%50[A-Z]\n", &n, s)==2)
	{
		int ans=0;
		for(int i=2;s[i];i++)
		{
			if(s[i-2]=='A' && s[i-1]=='B' && s[i]=='C')
			{
				ans++;
			}
		}
		printf("%d\n", ans);
	}
	return 0;
}