def lscan;gets.split.map(&:to_i);end

# 1Gの商品を 1G 10x+1枚 => コスト1で10x+1-x = 9x+1減らす

@a, @b, @c = lscan

# 減らしたい枚数
r = @a+@b-@c

if @a + @b < @c
  puts "Impossible" # 10Gを1Gで支払えば増やせるのでWA
  exit
elsif @a + @b == @c
  if @b == 0
    puts "Impossible"
  else
    p 9
  end
    
  exit
else
  cost = 1
  x = ([r, @a].min - 1) / 9
  @a -= 9*x+1
  r -= 9*x+1
  
  a = [r, @a].min
  cost += a
  r -= a
  
  p cost + (r)*10
end