Cubes - 3
Vitek has at home 2identical setsofcubesof English letters, butduring the regularcleaningone ofthe cubes lost. Help Witek to determinewhich of thecubesis missinginone of the suites.
The first line contains the number of found cubes n (1 ≤ n ≤ 105) by Vitek, and the second line contains n characters depicted on each of the cubes.
Print the character on the lost cube, or the message "Ok", if Vitek was mistaken and no cube is lost.