CF479C Exams

Student Valera is an undergraduate student at the University. His end of term exams are approaching and he is to pass exactly $ n $ exams. Valera is a smart guy, so he will be able to pass any exam he takes on his first try. Besides, he can take several exams on one day, and in any order. According to the schedule, a student can take the exam for the $ i $ -th subject on the day number $ a_{i} $ . However, Valera has made an arrangement with each teacher and the teacher of the $ i $ -th subject allowed him to take an exam before the schedule time on day $ b_{i} $ ( $ b_{i}

Student Valera is an undergraduate student at the University. His end of term exams are approaching and he is to pass exactly $ n $ exams. Valera is a smart guy, so he will be able to pass any exam he takes on his first try. Besides, he can take several exams on one day, and in any order. According to the schedule, a student can take the exam for the $ i $ -th subject on the day number $ a_{i} $ . However, Valera has made an arrangement with each teacher and the teacher of the $ i $ -th subject allowed him to take an exam before the schedule time on day $ b_{i} $ ( $ b_{i}

Print a single integer — the minimum possible number of the day when Valera can take the last exam if he takes all the exams so that all the records in his record book go in the order of non-decreasing date.

In the first sample Valera first takes an exam in the second subject on the first day (the teacher writes down the schedule date that is 3). On the next day he takes an exam in the third subject (the teacher writes down the schedule date, 4), then he takes an exam in the first subject (the teacher writes down the mark with date 5). Thus, Valera takes the last exam on the second day and the dates will go in the non-decreasing order: 3, 4, 5. In the second sample Valera first takes an exam in the third subject on the fourth day. Then he takes an exam in the second subject on the fifth day. After that on the sixth day Valera takes an exam in the first subject.