#D8446. Heidi Learns Hashing (Hard)
Heidi Learns Hashing (Hard)
Heidi Learns Hashing (Hard)
Now Heidi is ready to crack Madame Kovarian's hashing function.
Madame Kovarian has a very strict set of rules for name changes. Two names can be interchanged only if using the following hashing function on them results in a collision. However, the hashing function is parametrized, so one can always find a set of parameters that causes such a collision. Heidi decided to exploit this to her advantage.
Given two strings w_1, w_2 of equal length n consisting of lowercase English letters and an integer m.
Consider the standard polynomial hashing function:
H_p(w) := \left( ∑_{i=0}^{|w|-1} w_i r^i \right) \mbox{mod}(p)
where p is some prime, and r is some number such that 2≤ r ≤ p-2.
The goal is to find r and a prime p (m ≤ p ≤ 10^9) such that H_p(w_1) = H_p(w_2).
Strings w_1 and w_2 are sampled independently at random from all strings of length n over lowercase English letters.
Input
The first line contains two integers n and m (10 ≤ n ≤ 10^5, 2 ≤ m ≤ 10^5).
The second and the third line, respectively, contain the words w_1, w_2 that were sampled independently at random from all strings of length n over lowercase English letters.
Output
Output integers p, r.
p should be a prime in the range [m, 10^9] and r should be an integer satisfying r∈ [2,p-2].
At least one solution is guaranteed to exist. In case multiple solutions exist, print any of them.
Examples
Input
10 5 bgcbaaaaaa cccaaaaaaa
Output
5 2
Input
10 100 melodypond riversongg
Output
118219 79724
Note
In the first example, note that even though p=3 and r=2 also causes a colision of hashes, it is not a correct solution, since m is 5 and thus we want p≥ 5.
In the second example, we are aware of the extra 'g' at the end. We just didn't realize that "River Song" and "Melody Pond" have different lengths...
inputFormat
Input
The first line contains two integers n and m (10 ≤ n ≤ 10^5, 2 ≤ m ≤ 10^5).
The second and the third line, respectively, contain the words w_1, w_2 that were sampled independently at random from all strings of length n over lowercase English letters.
outputFormat
Output
Output integers p, r.
p should be a prime in the range [m, 10^9] and r should be an integer satisfying r∈ [2,p-2].
At least one solution is guaranteed to exist. In case multiple solutions exist, print any of them.
Examples
Input
10 5 bgcbaaaaaa cccaaaaaaa
Output
5 2
Input
10 100 melodypond riversongg
Output
118219 79724
Note
In the first example, note that even though p=3 and r=2 also causes a colision of hashes, it is not a correct solution, since m is 5 and thus we want p≥ 5.
In the second example, we are aware of the extra 'g' at the end. We just didn't realize that "River Song" and "Melody Pond" have different lengths...
样例
10 100
melodypond
riversongg
181 59
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