Problem:
Score : 300 points

Problem Statement

You are given a string S of length N consisting of A, C, G and T. Answer the following Q queries:

Query i (1 \leq i \leq Q): You will be given integers l_i and r_i (1 \leq l_i < r_i \leq N). Consider the substring of S starting at index l_i and ending at index r_i (both inclusive). In this string, how many times does AC occurs as a substring?

Notes

A substring of a string T is a string obtained by removing zero or more characters from the beginning and the end of T.

For example, the substrings of ATCODER include TCO, AT, CODER, ATCODER and (the empty string), but not AC.

Constraints

2 \leq N \leq 10^5

1 \leq Q \leq 10^5

S is a string of length N.

Each character in S is A, C, G or T.

1 \leq l_i < r_i \leq N

Input

Input is given from Standard Input in the following format:

N Q
S
l_1 r_1
:
l_Q r_Q

Output

Print Q lines. The i-th line should contain the answer to the i-th query.

Sample Input 1

8 3
ACACTACG
3 7
2 3
1 8

Sample Output 1

2
0
3

Query 1: the substring of S starting at index 3 and ending at index 7 is ACTAC. In this string, AC occurs twice as a substring.

Query 2: the substring of S starting at index 2 and ending at index 3 is CA. In this string, AC occurs zero times as a substring.

Query 3: the substring of S starting at index 1 and ending at index 8 is ACACTACG. In this string, AC occurs three times as a substring.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) throws Exception {
	    String[] lines = Io.read();

	    String baseStr = lines[1];
	    int[][] questions = parse(lines);

	    List<Integer> indexes = new ArrayList<Integer>();
	    for (int i = 0; i < baseStr.length(); i++) {
            int idx = baseStr.indexOf("AC", i);
            if (idx >= 0) {
                indexes.add(idx);
                i = idx + 1;
            }
        }

	    for (int i = 0; i < questions.length; i++) {
            int count = 0;

            int start = questions[i][0] - 1;
            int end = questions[i][1] - 1;

            for (int j = 0; j < indexes.size(); j++) {
                int acIdx = indexes.get(j);
                if (acIdx >= start && acIdx + 1 <= end) {
                    count++;
                }
            }

	        Io.write(count);
        }
    }

    private static int[][] parse(String[] lines) {
        String[] first = lines[0].split(" ");

        int q = Integer.parseInt(first[1]);
        int[][] parsed = new int[q][2];

        for (int i = 0; i < q; i++) {
            String[] tmp = lines[i + 2].split(" ");
            parsed[i][0] = Integer.parseInt(tmp[0]);
            parsed[i][1] = Integer.parseInt(tmp[1]);
        }
        return parsed;
    }
}

class Io {

    /**
     * 標準入力から1行ずつ受け取る
     * @return
     * @throws IOException
     */
    public static String[] read() throws IOException
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        List<String> inputs = new ArrayList<>();
        String line;
        while ((line = br.readLine()) != null) {
            if (line.equals(""))
                break;

            inputs.add(line);
        }
        br.close();
        return inputs.toArray(new String[0]);
    }

    /**
     * 標準出力
     * @param answer
     */
    public static void write(int answer)
    {
        System.out.println(answer);
    }
}