Script to find greatest prime factor.

Will this work and/or what should I do to improve it?

n = 2
peter = gets
until n > peter**0.5
if peter % n == 0
peter = peter / n
n = 2
else
n = n + 1
end
end
print peter

Code Ruby:

---

input = gets.to_i
 
# this code is the sieve of Eratosthenes, I just googled for it
sieve = []
for i in 2 .. input
  sieve[i] = i
end
 
for i in 2 .. Math.sqrt(input)
  next unless sieve[i]
  (i*i).step(input, i) do |j|
    sieve[j] = nil
  end
end
 
# here we look for the highest prime factor
sieve.compact.reverse.each do |p|
  if input % p == 0
    print p
    exit
  end
end

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