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: Wrong Answer)

#include <stdio.h>
int main()
{
    char a[51];
    int count,n,i;
    count=0;
    scanf("%d",&n);
    scanf("%s",a);
    for(i=0;i<n;i++){
        if(a[i]=='A'){
            i++;
            if(a[i]=='B'&&i<n){
                i++;
                if(a[i]=='C'&&i<n)
                    count++;
                    else continue;
            }
            else continue;
        }
        else continue;
    }
    printf("%d",count);
    return 0;
}