문제2495--Common Permutation

### 2495: Common Permutation

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#### 문제 설명

Given two strings of lowercase letters, a and b, print the longest string x of lowercase letters such that there is a permutation of x that is a subsequence of a and there is a permutation of x that is a subsequence of b.

#### 입력 설명

Input file contains several lines of input. Consecutive two lines make a set of input. That means in the input file line 1 and 2 is a set of input, line 3 and 4 is a set of input and so on. The first line of a pair contains a and the second contains b. Each string is on a separate line and consists of at most 1000 lowercase letters.

#### 출력 설명

For each set of input, output a line containing x. If several x satisfy the criteria above, choose the first one in alphabetical order.

#### 입력 예시 Copy

pretty
women
walking
down
the
street

#### 출력 예시 Copy

e
nw
et