# Flat array
#input =  [[1,2,[3]],4, 5, [6,7]]
# How to use it:
# 1. ruby flat.rb
# 2. Type the input e.g: [[1,2,[3]],4, 5, [6,7]]
# 3. Type Enter and Ctrl-D
# it will print the oputput

def flat_array (input_a)
  flatten = [];
  for i in input_a
    if i.instance_of? Array
      flatten.concat(flat_array(i))
    else
      flatten.push(i)
    end
  end
  flatten
end

input = $stdin.read
input = eval(input.strip! || input);
print flat_array(input), "\n"