Olympic Parade#7518
SEERC organizing committee decided to make this year's opening ceremony unusual by organizing a contestant parade in the city streets. This year, people (contestants, coaches, and guests), representing universities from participating countries, will walk through the streets, trying to impress spectators with original costumes and loud songs. Each university is represented by a group of people and has a unique identifier () that is carried by each member of the group. To make the parade well organized and entertaining, each group must be lined up in several rows, each consisting of people.
However, exactly one university was not able to line up according to this rule, and you need to find its .
The first line contains integers and , separated by a space (1 < N < 1\,000\,000, 2 < K < 1\,000). The following lines each contain an integer C_j (0 < C_j < 1\,000\,000\,000), which is the of the university for the -th person (1 \leq j \leq N).
Output a single integer — the of the university that cannot be organized according to the rules.
Example 3