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 (Clang 3.8.0) (judge verdict: Accepted)

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

#define A_CHARACTER 'A'
#define B_CHARACTER 'B'
#define C_CHARACTER 'C'

int main()
{
	int lettersAmount, printOutput = 0;	
	char inputChar;
	scanf("%d", &lettersAmount);
	char *letterArray;

	letterArray = malloc(sizeof(char) * lettersAmount);

	for (int i = 0; i < lettersAmount + 1; i++)
	{
		scanf("%c", &inputChar);
		letterArray[i - 1] = inputChar;
	}

	for (int i = 0; i < lettersAmount; i++)
	{
		char stringABC[3];
		if (letterArray[i] == A_CHARACTER && i < lettersAmount && i + 1 < lettersAmount && i + 2 < lettersAmount)
		{
			stringABC[0] = letterArray[i];
			stringABC[1] = letterArray[i + 1];
			stringABC[2] = letterArray[i + 2];
		}
		if (stringABC[0] == 'A' && stringABC[1] == 'B' && stringABC[2] == 'C')
		{
			printOutput++;
		}

		stringABC[0] = NULL;
		stringABC[1] = NULL;
		stringABC[2] = NULL;
	}

	printf("%d \n", printOutput);
	return 0;
}