REQUIREMENTS: C$++$ only

Design and implement a program to generate all permutations of the set of least n

positive integers.

INPUT:

$$ an integer n with $1<=$ n $<=30.$

OUTPUT:

$$ The tag $$There are x permutations of the set $\{1,2,...,$ n$\}$:$,$ where x $=$ n$!$

$$ a list of all permutations of the set $\{1,2,...,$ n$\},$ one per line.

EXAMPLE OUTPUT:

There are $6$ permutations of the set $\{1,2,3\}$:

$123$

$132$

$312$

$321$

$231$

$213$