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: Wrong Answer)

#include <stdio.h>
int main(){
    int N;
    char s[51];
    scanf("%d",&N);
    int a,count;
    a=0,count=0;
    for(int i =0;i<N;i++){
        scanf("%c",&s[i]);
        
        if(s[i]=='A'){
            a=1;
        }else if(s[i]=='B'){
            if(a==1){
                a = 2 ;
            }else{
                a=0;
            }
        }else if(s[i] == 'C'){
            if(a==2){
                count++;
            }else{
                a =0;
            }
        }
    }
    printf("%d",count);
    return 0;
}