Cubes - 3#2807
Vitek had at home 2 identical sets of cubes with English letters. After a recent cleaning, one cube was lost. Help Vitek determine which cube is missing from the sets.
The first line contains the number of cubes found by Vitek (1 \leq n \leq 10^5).The second line contains characters, each representing a cube that was found.
Print the letter on the missing cube, or print "Ok" if Vitek was mistaken and no cube is missing.
Beispiel 1