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 PyPy3 (2.4.0) (judge verdict: Accepted)

from __future__ import print_function

import sys
input = sys.stdin.readline

def eprint(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)
    return

# import math
# import string
# import fractions
# from fractions import Fraction
# from fractions import gcd

# def lcm(n,m):
#     return int(n*m/gcd(n,m))

# import re
# import array
# import copy
# import functools
# import operator

# import collections
# import itertools
# import bisect
# import heapq


# from heapq import heappush
# from heapq import heappop
# from heapq import heappushpop
# from heapq import heapify
# from heapq import heapreplace

# from queue import PriorityQueue as pq

# def reduce(p, q):
#     common = fractions.gcd(p, q)
#     return (p//common , q//common )
# # from itertools import accumulate
# # from collections import deque

# from operator import mul
# from functools import reduce

# def combinations_count(n, r):
#     r = min(r, n - r)
#     numer = reduce(mul, range(n, n - r, -1), 1)
#     denom = reduce(mul, range(1, r + 1), 1)
#     return numer // denom

# import random

def main():
    n=int(input())
    s=input().strip()
    cnt=0
    for i in range(0,n):
            if s[i:i+3]=="ABC":
                cnt+=1
            else:
                pass
    print(cnt)
    return

if __name__ == '__main__':
    main()