Given two strings of lowercase letters a and b. Print the longest string x that is simultaneously a substring of the permutation of a and a substring of the permutation of b.
Consists of multiple test cases, each contains a pair of lines. The first line of a pair contains a and the second line contains b. Each string is on a separate line and consists of at most 1000 lowercase letters.
For each subsequent pair of input lines print a line containing x. If several x satisfy the criteria above, choose the first one in alphabetical order.