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)

from fractions import gcd
# from datetime import date, timedelta
from heapq import*
import math
from collections import defaultdict, Counter, deque
from bisect import *
import itertools
import fractions
# import sys
# sys.setrecursionlimit(10 ** 7)
MOD = 10 ** 9 + 7
# input = sys.stdin.readline


def lcm(a, b):
    return a * b / fractions.gcd(a, b)

def main():
    n = int(input())
    s = input()
    ans = 0
    for i in range(n - 3):
        if s[i:i + 3] == "ABC":
            ans += 1
    print(ans)
    # n, m = map(int, input().split())
    # a = list(map(int, input().split()))

    # g = lcm(a[0], a[1])
    # for i in range(2, n):
    #     g = lcm(g, a[i])
    # if g // 2 > m:
    #     print(0)
    #     exit()
    # print(g)
    # print(math.ceil(m//g + 0.5))



    


if __name__ == '__main__':
    main()