Yahoo280919

 This problem was asked by Yahoo.

You are given a string of length N and a parameter k. The string can be manipulated by taking one of the first k letters and moving it to the end.

Write a program to determine the lexicographically smallest string that can be created after an unlimited number of moves.

For example, suppose we are given the string daily and k = 1. The best we can create in this case is ailyd