public/subjects/union.en.md

## union

### Instructions

Write a program that takes two `strings` and displays, without doubles, the
characters that appear in either one of the `strings`.

The display will be in the order characters appear in the command line, and
will be followed by a newline(`'\n'`).

If the number of arguments is different from 2, the program displays newline(`'\n'`).

### Usage

```console
student@ubuntu:~/student/union$ go build
student@ubuntu:~/student/union$ ./union zpadinton "paqefwtdjetyiytjneytjoeyjnejeyj" | cat -e
zpadintoqefwjy$
student@ubuntu:~/student/union$ ./union ddf6vewg64f gtwthgdwthdwfteewhrtag6h4ffdhsd | cat -e
df6vewg4thras$
student@ubuntu:~/student/union$ ./union "rien" "cette phrase ne cache rien" | cat -e
rienct phas$
student@ubuntu:~/student/union$ ./union | cat -e
$
student@ubuntu:~/student/union$ ./union "rien" | cat -e
$
student@ubuntu:~/student/union$
```