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 Python (3.4.3) (judge verdict: Wrong Answer)

n = int(input())
s = input()
cnt = 0
flg = 0
for i in range(n):
    if flg == 0:
        if s[i] == "A":
            flg = 1
    elif flg == 1:
        if s[i] == "B":
            flg = 2
        else:
            flg = 0
    elif flg == 2:
        if s[i] == "C":
            cnt += 1
        flg = 0

print(cnt)