Problem:
Range Sum Query

Write a program which manipulates a sequence A = {a1, a2, . . . , an} with the following operations:

add(i, x): add x to ai.

getSum(s, t): print the sum of as, as+1,...,at.

Note that the initial values of ai (i = 1, 2, . . . , n) are 0.

Input

n q
com1 x1 y1
com2 x2 y2
...
comq xq yq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, q queries are given where com represents the type of queries. '0' denotes add(xi, yi) and '1' denotes getSum(xi, yi).

Output

For each getSum operation, print the sum in a line.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

If comi is 0, then 1 ≤ xi ≤ n, 0 ≤ yi ≤ 1000.

If comi is 1, then 1 ≤ xi ≤ n, 1 ≤ yi ≤ n.

Sample Input 1

3 5
0 1 1
0 2 2
0 3 3
1 1 2
1 2 2

Sample Output 1

3
2

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Convert;
using static System.Math;
//using Debug;
//using static System.Globalization.CultureInfo;
using System.Text;
class Program
{
    static void Main(string[] args)
    {
        Solve();
        //WriteLine(Solve());
    }
    static void Solve()
    {
        Func<long,long,long> func = (long v1, long v2) => v1 + v2;
        var nq = Input.ar;
        var seg = new SegmentTree<long>(nq[0], 0, func, func);
        var res = new List<long>();
        while (nq[1]-- > 0)
        {
            var cxy = Input.ar;
            if (cxy[0] == 0)
                seg.Update(cxy[1]-1, cxy[2]);
            else res.Add(seg.query(cxy[1] - 1, cxy[2]));
        }
        WriteLine(string.Join("\n", res));
    }
}

public class Input
{
    public static string read => ReadLine();
    public  static int[] ar => Array.ConvertAll(read.Split(' '), int.Parse);
    public  static int num => ToInt32(read);
    public static long[] arL => Array.ConvertAll(read.Split(' '), long.Parse);
    public  static long numL => ToInt64(read);
    public static char[][] gred(int h) 
        => Enumerable.Repeat(0, h).Select(v => read.ToCharArray()).ToArray();
    public static int[][] ar2D(int num)
        => Enumerable.Repeat(0, num).Select(v => ar).ToArray();
    public static long[][] arL2D(int num)
        => Enumerable.Repeat(0, num).Select(v => arL).ToArray();
    public static T getValue<T>(string g)
    {
        var t = typeof(T);
        if (t == typeof(string))
            return (T)(object)g;
        if (t == typeof(int))
            return (T)(object)int.Parse(g);
        if (t == typeof(bool))
            return (T)(object)bool.Parse(g);
        if (t == typeof(long))
            return (T)(object)long.Parse(g);
        return default(T);
    }
    public const long Inf = (long)1e18;
    public const double eps = 1e-6;
    public  const string Alfa = "abcdefghijklmnopqrstuvwxyz";
    public  const int MOD = 1000000007;
}

public class SegmentTree<T>
{
    private List<T> item;
    private int _num;
    private Func<T, T, T> _func;
    private Func<T, T, T> updateFunc;
    private T _init;

    private int Parent(int index)
        => (index + 1) / 2 - 1;
    private int Left(int index)
        => 2 * index + 1;
    private int Right(int index)
        => 2 * (index + 1);

    public SegmentTree(int num, T init, Func<T, T, T> func, Func<T, T, T> updateFunc = null)
    {
        _func = func;
        _num = 1;
        _init = init;
        this.updateFunc = updateFunc ?? ((T val1, T val2) => val2);
        while (_num < num)
            _num *= 2;
        item = new List<T>(2 * _num - 1);
        for (var i = 0; i < 2 * _num - 1; i++)
            item.Add(init);
    }
    public void Update(int index, T value)
    {
        index += _num - 1;
        item[index] = updateFunc(item[index], value);
        while (Parent(index) >= 0)
        {
            index = Parent(index);
            item[index] = _func(item[Left(index)], item[Right(index)]);
        }
    }
    public T query(int left, int right)
        => query(left, right, 0, 0, _num);
    private T query(int left, int right, int k, int l, int r)
    {
        if (r <= left || right <= l) return _init;
        if (left <= l && r <= right) return item[k];
        else
            return _func(query(left, right, Left(k), l, (l + r) / 2), query(left, right, Right(k), (l + r) / 2, r));
    }
}