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: Accepted)

#include <stdio.h>
typedef long long ll;

int main(void) {
    int N;
    scanf("%d", &N);

    char S[N];
    scanf("%s", S);

    int ans = 0;
    for(int i = 0; i < N - 2; ++i) {
        if(S[i] == 'A' && S[i + 1] == 'B' && S[i + 2] == 'C') {
            ans ++;
            i += 2;
        }
    }
    printf("%d\n", ans);

    return 0;
}