n, h = gets.split.map(&:to_i)

as = []
bs = []
n.times do
    a, b = gets.split.map(&:to_i)
    as << a
    bs << b
end

amx = as.max
bsum = 0
bcnt = 0
bs.each do |bi|
    if bi > amx
        bsum += bi
        bcnt += 1
    end
end

puts (h - bsum + amx - 1)/amx + bcnt
