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>

int compare_int_big(const void *a,const void *b){
    return *(int *)b - *(int *)a;
}

int compare_int_small(const void *a,const void *b){
    return *(int *)a - *(int *)b;
}

int main(void)
{
    int ans = 0;

    int N;
    char S[51];
    int flag=0;

    scanf("%d",&N);
    scanf("%s",S);

    for(int i =0; i< N ; i++){
        if(S[i]=='A'){
            if(S[i+1]=='B'){
                if(S[i+2]=='C'){
                    ans++;
                }
            }
        }
    }

    printf("%d",ans);

    return 0;
}