n, h = gets.chomp.split(' ').map(&:to_i)
arr = []
n.times do
  arr << gets.chomp.split(' ').map(&:to_i)
end
arr.sort_by!{ |i| -i[1] }
count = 0
while h > 0 do
  first = arr[0]
  second = arr[1]
  second = [0, 0] if second.nil?
  if first[1] >= h
    count += 1
    h -= first[1]
  elsif first[0] >= second[1]
    count += 1
    h -= first[1]
    count += h % first[0] == 0 ? h / first[0] : h / first[0] + 1
    h = 0
  else
    count += 1
    if arr.count == 1
      h -= first[0]
    else
      h -= first[1]
      arr.shift
    end
  end
end
puts count