Range Sum Query with Updates using Fenwick Tree

You are given an array of integers and a sequence of operations. The operations are of two types:

• Update Operation: Replace the element at a given index with a new value.
• Sum Query: Compute the sum of the subarray from index l to r (inclusive).

You must perform these operations efficiently. A common technique is to use a Fenwick Tree (also known as a Binary Indexed Tree). The Fenwick Tree can be updated and queried in \(O(\log n)\) time.

Note: All indices in the input are 0-indexed.

Your solution should read the input from stdin and output the results of all sum queries to stdout.

inputFormat

The first line contains two integers n and q: the number of elements in the array and the number of operations, respectively.

The second line contains n space-separated integers representing the array.

Each of the following q lines contains an operation in one of the two formats:

• u index value: Update the element at position index to value.
• s l r: Output the sum of the elements in the range [l, r].

outputFormat

For each sum query (operations starting with s), output a single integer on its own line representing the sum of the specified subarray.

## sample

5 5
1 2 3 4 5
s 1 3
u 2 10
s 1 3
u 0 6
s 0 4

9
16
27

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