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 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>

#define max(a,b) ((a)>(b))?(a):(b);
#define min(a,b) ((a)>(b))?(b):(a);

int main(void)
{
	int cnt=0, nc=0, n;
	scanf("%d\n", &n);
	char s[51];
	char* sp = s;
	scanf("%s", sp);

	while (*sp)
	{
		if (nc + 'A' != *sp)
		{
			nc = 0;
		}
		if (nc+'A'==*sp)
		{
			nc++;
			if (nc + 'A' == 'C' + 1)
			{
				nc = 0;
				cnt++;
			}
		}
		sp++;
	}

	printf("%d", cnt);
}