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>

int main(void){

  int n;
  scanf("%d\n", &n);
  char s[n];
  for (int i = 0; i < n; i++) {
    scanf("%c", &s[i]);
  }
  int count = 0;

  for (int i = 0; i < n-2; i++) {
    if (s[i] == 'A') {
      if (s[i+1] == 'B' && s[i+2] == 'C') {
        count++;
        i += 2;
      }
    }
  }

  printf("%d\n", count);

  return 0;
}