Matching Names

2000ms

262144K

Description:

Teachers of one programming summer school decided to make a surprise for the students by giving them names in the style of the "Hobbit" movie. Each student must get a pseudonym maximally similar to his own name. The pseudonym must be a name of some character of the popular saga and now the teachers are busy matching pseudonyms to student names.

There are n students in a summer school. Teachers chose exactly n pseudonyms for them. Each student must get exactly one pseudonym corresponding to him. Let us determine the relevance of a pseudonym b to a student with name a as the length of the largest common prefix a and b. We will represent such value as $\text{[math]}$ . Then we can determine the quality of matching of the pseudonyms to students as a sum of relevances of all pseudonyms to the corresponding students.

Find the matching between students and pseudonyms with the maximum quality.

Input:

The first line contains number n (1 ≤ n ≤ 100 000) — the number of students in the summer school.

Next n lines contain the name of the students. Each name is a non-empty word consisting of lowercase English letters. Some names can be repeating.

The last n lines contain the given pseudonyms. Each pseudonym is a non-empty word consisting of small English letters. Some pseudonyms can be repeating.

The total length of all the names and pseudonyms doesn't exceed 800 000 characters.

Output:

In the first line print the maximum possible quality of matching pseudonyms to students.

In the next n lines describe the optimal matching. Each line must have the form a b (1 ≤ a, b ≤ n), that means that the student who was number a in the input, must match to the pseudonym number b in the input.

The matching should be a one-to-one correspondence, that is, each student and each pseudonym should occur exactly once in your output. If there are several optimal answers, output any.

Sample Input:

5
gennady
galya
boris
bill
toshik
bilbo
torin
gendalf
smaug
galadriel

Sample Output:

Note:

The first test from the statement the match looks as follows:

bill → bilbo (lcp = 3)
galya → galadriel (lcp = 3)
gennady → gendalf (lcp = 3)
toshik → torin (lcp = 2)
boris → smaug (lcp = 0)

Informação

Provedor Codeforces

Código CF566A