A. New Year and Hurry time limit per test 1 second memory limit per test 256 megabytes Limak is going to participate in a contest on the last day of the 2016. The contest will start at 20:00 and will last four hours, exactly until midnight. There will be n problems, sorted by difficulty, i.e. problem 1 is the easiest and problem n is the hardest. Limak knows it will take him 5·i minutes to solve the i-th problem. Limak’s friends organize a New Year’s Eve party and Limak wants to be there at midnight or earlier. He needs k minutes to get there from his house, where he will participate in the contest first. How many problems can Limak solve if he wants to make it to the party?