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 C (GCC 5.4.1) (judge verdict: Accepted)


#include<stdio.h>

void count(char s[], int n){
    int cnt = 0;
    for(int i = 0; i < n - 2; i++){
        if(s[i] == 'A' && s[i + 1] == 'B' && s[i + 2] == 'C'){
            cnt ++;
            i += 2;
        }
    }
    printf("%d\n", cnt);
}

int main(void){
    int n;
    scanf("%d", &n);
    char s[n + 1];
    scanf("%s", s);
    count(s, n);
    return 0;
}