nthr(n,r) <= n^(1/r)
nthroot(n,r)=
a = n/r
g = n
> g!=a
g = a
a = (1/r)*(((r-1)*g)+(n/(g^(r-1))))
<
<= a
.
#.output(nthr(2,2))
#.output(nthroot(2,2))