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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

// https://atcoder.jp/contests/abc122/tasks/abc122_c
namespace CGeTAC
{
    class Program
    {
        static void Main(string[] args)
        {
            // 入力の取得
            var inputs = Console.ReadLine().Split().Select(int.Parse).ToArray();
            var n = inputs[0];
            var q = inputs[1];
            var str = Console.ReadLine().ToCharArray();

            // str 内の AC 累積数一覧を作成
            var acCount = 0;
            var acSummary = new int[n];
            acSummary[0] = 0;
            for (var i = 1; i < n; i++)
            {
                if (str[i - 1] == 'A' && str[i] == 'C') acCount++;
                acSummary[i] = acCount;
            }

            var answers = new int[q];
            for (var i = 0; i < q; i++)
            {
                var range = Console.ReadLine().Split().Select(int.Parse).ToArray();
                var left = range[0] - 1;
                var right = range[1] - 1;
                answers[i] = acSummary[right] - acSummary[left];
            }

            // 解答の出力
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
            foreach (var answer in answers)
            {
                Console.WriteLine(answer);
            }
            Console.Out.Flush();
        }
    }
}