function parseInt(x) parse(Int, x) end
function main()
  n = parseInt.(split(readline()))
  x = [Int[] for i in 1:n[1]]
  for i in 1:n[1]
    x[i] = parseInt.(split(readline()))
  end
  maxa = 0
  for i in 1:n[1]
    if x[i][1] > maxa
      maxa = x[i][1]
    end
  end
  allb = [0 for i in 1:n[1]]
  for i in 1:n[1]
    allb = x[i][2])
  end
  useb = sort(allb, rev=true)
  hp = n[2]
  count = 0
  zzz = 1
  while(sort[zzz] > maxa)
    if hp > 0
      hp -= useb[i]
      count += 1
    end
    zzz += 1
  end
  if hp > 0
    if hp%maxa == 0
      count += div(hp, maxa)
    else
      count += div(hp, maxa)+1
    end
  end
  print(count)
end

main()