Efficient Pre-Sum Update

Given an array $a_1$, $a_2$, …... $a_n$ of length n and q queries. Each query consists of two types of operation. 1) First type of query consists of 2 integers -- *x* and *y*. You need to replace the element present at $x^{th}$ index of the array with value y. 2) In Second type of query take prefix-sum of updated array and print left most index and right most index having positive number as it