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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function Main(input) {
  input.trim();
 input = input.split("\n");
 var arr = input[1].split("");
 var N = input[0];
 var point = 0;
 var ans = 0;
 for(var i=0;i<N;i++){
   switch(point){
     case 0:
     if(arr[i]=="A"){
       point = 1;
     }
     break;
     case 1:
     if(arr[i]=="B"){
       point = 2;
     }else{
       point = 0;
     }
     break;
     case 2:
     if(arr[i]=="C"){
       ans++;
     }
     point = 0;
     break;
   }
 }
 console.log(ans)
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));