N = gets.to_i
A = N.times.map{
      gets.to_i
    }

def generate_nums size
  (0...size).map{|i| rand(0...(size-i))}
end

def dec_nums nums
  array = (0...nums.size).to_a
  nums.map{|i| array.delete_at(i)}
end

def check_nums nums
  nums.each.with_index{|num, i|
    return i if nums[i] == A[i]
  }
  return nil
end

def change_nums nums, index
  nums[index] = rand(0...(nums.size - index))
  nums
end

if A.uniq.size == 1
  p -1
else
  nums = generate_nums N
  while (ng = check_nums(dec_nums(nums))) != nil
    change_nums nums, ng
  end
  dec_nums(nums).each{|i| p i }
end