Input
3 3
...
.*.
...
Output
Not unique
Input
4 4
..**
*...
*.**
....
Output
<>**
*^<>
*v**
<><>
Input
2 4
*..*
....
Output
*<>*
<><>
Input
1 1
.
Output
Not unique
Input
1 1
*
Output
*