Describe how you would solve the following problem using map-reduce. You should explain how the input is mapped into (key, value) pairs by the map stage, i.e., specify what is the key and what is the associated value in each pair, and, if needed, how the key(s) and value(s) are computed. Then you should explain how the (key, value) pairs produced by the map stage are processed by the reduce stage to get the final answer(s). The input data for this problem is a large collection of weather observations. Each line of the input data gives information about a single observation from a particular weather station, and contains the following: station#, city, state, elevation, year, month, day, time, temperature, precipitation. Print the maximum recorded temperature for each city in the database. The output should have a single line for each city and the highest temperature found in any time for that city. Note that city names are not necessarily unique (there are over 20 cities named Lincoln in the United States), but you may assume that no single state has two cities with the same name. The output need not be sorted in any particular order