You are given $n$ string $S_1, S_2,...,S_n$.
Find the shortest string $S$ that $S_1, S_2,...,S_n$ are substrings of $S$.
### Input
- The first line contains an integer $n$.
- The next $n$ lines, each line contains a string $S_i$.
### Output
- Print the shortest string.
### Constraints
- $1 \le n \le 20$.
- $1 \le |S_i| \le 100$.
### Example
Input:
```
3
ab
bcc
da
```
Output:
```
dabcc
```
