AtCoder ABC #076

abc076-a.rb

r = gets.chomp.to_i
g = gets.chomp.to_i
puts 2 * g - r

abc076-b.rb

n = gets.chomp.to_i
k = gets.chomp.to_i
x = 1
n.times do
  a = x * 2
  b = x + k
  x = [a, b].min
end
puts x

abc076-c.rb

s = gets.chomp
t_ = gets.chomp

ns = s.length
nt = t_.length
arr = []
(ns - nt + 1).times do |i|
  x = s.clone
  ss = s[i..(i + nt - 1)]
  ok = true
  nt.times do |j|
    if ss[j] != "?" && ss[j] != t_[j]
      ok = false
    end
  end
  if ok
    x[i, nt] = t_
    arr << x
  end
end
if arr.empty?
  puts "UNRESTORABLE"
else
  arr.sort!
  ans = arr[0].gsub("?", "a")
  puts ans
end