Time limit : 2sec / Memory limit : 256MB
Score : 200 points
Problem Statement
Iroha has a sequence of N strings S1,S2,…,SN. The length of each string is L.
She will concatenate all of the strings in some order, to produce a long string.
Among all strings that she can produce in this way, find the lexicographically smallest one.
Here, a string s=s1s2s3...sn is lexicographically smaller than another string t=t1t2t3...tm if and only if one of the following holds:
There exists an index i(1≦i≦min(n,m)), such that sj=tj for all indices j(1≦j<i), and si<ti.
si=ti for all integers i(1≦i≦min(n,m)), and n<m.