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 Rust (1.42.0) (judge verdict: Accepted)

extern crate proconio;
use proconio::{input, marker::Chars};
fn main() {
  input!{
    n: usize,
    s: Chars,
  };

  let mut ans = 0;
  for i in 0..n-2 {
    if cmp(&s[i..i+3]){
      ans += 1;
    }
  }
  println!("{}", ans);
}

fn cmp(l: &[char]) -> bool {
  let arr = "ABC".chars().collect::<Vec<char>>();
  for j in 0..3 {
    if arr[j] != l[j] {
      return false
    }
  }
  true
}