Customers Above Threshold

You are given n transactions. Each transaction consists of a customer identifier and an amount spent. For each customer, compute the total amount spent over all transactions. Let \(S_i\) represent the sum of spending for customer \(i\). The task is to output all customer identifiers for which \(S_i > t\), where \(t\) is a given threshold.

If no customer fulfills the condition, output None.

The output list should be sorted alphabetically.

inputFormat

Input is read from stdin. The first line contains two integers n and t separated by a space. Here, n is the number of transactions and t is the threshold value. Each of the following n lines contains a string and an integer separated by a space, representing a customer identifier and the amount spent in that transaction.

outputFormat

Output to stdout a single line containing the customer identifiers that have spent more than t, sorted in alphabetical order and separated by a single space. If no customer meets the threshold, print None.## sample

5 500
alice 200
bob 300
alice 400
charlie 100
bob 250

alice bob