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 Ruby (judge verdict: Accepted)

class BinaryIndexTree
  attr_reader :bit, :size

  def initialize(size, init: 0)
    @bit = Array.new(size, init)
    @size = size
  end

  def sum(i)
    s = 0

    while i > 0
      s += bit[i]
      i -= i & -i
    end

    s
  end

  def add(i, x)
    while i < size
      bit[i] += x
      i += i & -i
    end
  end
end

N, Q = gets.split.map(&:to_i)
bit = BinaryIndexTree.new(N + 1)

Q.times do
  com, x, y = gets.split.map(&:to_i)

  if com == 0
    bit.add(x, y)
  else
    puts bit.sum(y) - bit.sum(x - 1)
  end
end