Range update point query

Implement a structure over an array of n zeros (indices 0..n-1) supporting range-update and point-query, each in O(log n). Process operations: ["update", l, r, v] adds v to every element in the inclusive range [l, r]; ["get", i] returns the current value at index i. Use a Fenwick tree over a difference array: a range update is two point updates (+v at l, -v at r+1) and a point query is a prefix sum. Return the list of get results in order.