Closest Pair of Sum

Given an array of integers and a target integer, return the indices of two numbers such that they add up to the closest possible sum to the target. If multiple pairs have the same distance to the target, return the pair with the smallest indices. Input is a single line of space-separated integers followed by the target integer. Example input: '10 2 5 6 3 8 7 12 9 15 13 10'. Example output: '2 3'.