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

a,b = lscan.map(&:to_r)

a %= 12

ta = a*5+b/12

if ta == b
  p 0
  exit
end

if ta < b
  b -= 60
  a += 1
end
  
99999.times do |i|
  lb = b + i.to_r/60
  la = a*5 + lb / 12
  if la < lb
    p i-1
    exit
  end
  if la == lb
    p i
    exit
  end
end