Drop duplicate values from string

I'm using this formulat to print out a string of numbers;


here's the current formula: =SUBSTITUTE(TRIM(A1&" "&B1&" "&C1)," ","~")

But I need to modify it so that it dumps duplicate values like; 4~4~6 ----> 4~6

so if A1 and/or B2 and/or C1 are equal to one another; only one of the two or more duplicate values is displayed.

Any thoughts?