wtf, rev.0

#!/usr/bin/env ruby
n = STDIN.readline.strip.to_i
numbers = STDIN.readline.split(/\s/).compact.map(&:to_i)
answer = STDIN.readline.strip.to_i

if (numbers.length != n) then
  puts "array size mismatch"; exit
end

def exit_no_solution(); puts "no solution"; exit; end

min = numbers.reduce(numbers[0] * 2) {|s, i| s -= i }
exit_no_solution if (answer < min)

max = numbers.reduce(0) {|s, i| s += i }
exit_no_solution if (answer > max)

[:-, :+].repeated_permutation(n-1) do |signs|
  signs.insert(0, :+)
  result = (0..n-1).each.reduce(0) do |s, i|
    s = s.method(signs[i]).call(numbers[i])
  end
  next if result != answer
  formula = (0..n-1).each.reduce("") do |s, i|
    s += (" %s " % signs[i].to_s) if i != 0
    s += numbers[i].to_s
  end
  puts "#{answer} = #{formula}"; exit
end
exit_no_solution