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 Ruby (2.3.3) (judge verdict: Wrong Answer)

num = gets.chomp.to_i
init = gets.chomp.chars
search = ["A","B","C"]
count = 0
i = 0
search_num = 0
while(i<(init.size))
    if (init[i] == search[search_num])&&(search_num <= 2)
        i += 1
        search_num += 1
    elsif search_num == 3
        search_num = 0
        count += 1
    else
        search_num = 0
        i += 1
    end
end 
puts count