CF659B Qualifying Contest

Very soon Berland will hold a School Team Programming Olympiad. From each of the $ m $ Berland regions a team of two people is invited to participate in the olympiad. The qualifying contest to form teams was held and it was attended by $ n $ Berland students. There were at least two schoolboys participating from each of the $ m $ regions of Berland. The result of each of the participants of the qualifying competition is an integer score from $ 0 $ to $ 800 $ inclusive. The team of each region is formed from two such members of the qualifying competition of the region, that none of them can be replaced by a schoolboy of the same region, not included in the team and who received a greater number of points. There may be a situation where a team of some region can not be formed uniquely, that is, there is more than one school team that meets the properties described above. In this case, the region needs to undertake an additional contest. The two teams in the region are considered to be different if there is at least one schoolboy who is included in one team and is not included in the other team. It is guaranteed that for each region at least two its representatives participated in the qualifying contest. Your task is, given the results of the qualifying competition, to identify the team from each region, or to announce that in this region its formation requires additional contests.

The first line of the input contains two integers $ n $ and $ m $ ( $ 2

Print $ m $ lines. On the $ i $ -th line print the team of the $ i $ -th region — the surnames of the two team members in an arbitrary order, or a single character "?" (without the quotes) if you need to spend further qualifying contests in the region.

In the first sample region teams are uniquely determined. In the second sample the team from region $ 2 $ is uniquely determined and the team from region $ 1 $ can have three teams: "Petrov"-"Sidorov", "Ivanov"-"Sidorov", "Ivanov" -"Petrov", so it is impossible to determine a team uniquely.