Maximize Total Donation

You are given n items, where each item is characterized by two integers: the starting bid \(b_i\) and the premium factor \(p_i\). Boboniu can accept at most \(k\) bids. When he accepts a bid, he obtains a donation equal to its premium factor.

Your task is to compute the maximum total donation Boboniu can receive by selecting up to \(k\) items with the highest premium factors.

Note: The starting bid \(b_i\) is provided with each item but does not affect the donation amount.

inputFormat

The first line contains two integers \(n\) and \(k\) (\(1 \leq k \leq n \leq 10^5\)), representing the number of items and the maximum number of accepted bids respectively.

Each of the following \(n\) lines contains two integers \(b_i\) and \(p_i\) (\(0 \leq b_i, p_i \leq 10^9\)), where \(b_i\) is the starting bid and \(p_i\) is the premium factor.

outputFormat

Output a single integer representing the maximum total donation Boboniu can collect.

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60