Favourite Bigram
Print the most frequent two-character substring (bigram); ties break lexicographically.
Input: one line with a lowercase string of length ≥ 2.
Output: the winning bigram.
Constraints:
- 2 ≤ |S| ≤ 105
Sample Tests
Input 1
ababab
Output 1
ab
Input 2
aabb
Output 2
aa
Discussion (opens after you solve — no spoilers before)
No comments yet.