Perfect numbers

You are given a natural number $n$. Print all perfect numbers not exceeding $n$. A perfect number equals the sum of its divisors other than itself: $6 = 1 + 2 + 3$, $28 = 1 + 2 + 4 + 7 + 14$.

A single integer $n$ ($6 \le n \le 10^4$).

A single line with the perfect numbers in increasing order, separated by spaces.

For each number find the sum of its divisors in an inner loop. It is enough to check divisors up to $\sqrt{x}$, not up to $x$: if $d$ is a divisor, so is $$. Write the condition as . Add separately and do not add itself.