{"raw_statement":[{"iden":"statement","content":"You have _n_ devices that you want to use simultaneously.\n\nThe _i_\\-th device uses _a__i_ units of power per second. This usage is continuous. That is, in λ seconds, the device will use λ·_a__i_ units of power. The _i_\\-th device currently has _b__i_ units of power stored. All devices can store an arbitrary amount of power.\n\nYou have a single charger that can plug to any single device. The charger will add _p_ units of power per second to a device. This charging is continuous. That is, if you plug in a device for λ seconds, it will gain λ·_p_ units of power. You can switch which device is charging at any arbitrary unit of time (including real numbers), and the time it takes to switch is negligible.\n\nYou are wondering, what is the maximum amount of time you can use the devices until one of them hits 0 units of power.\n\nIf you can use the devices indefinitely, print _\\-1_. Otherwise, print the maximum amount of time before any one device hits 0 power."},{"iden":"input","content":"The first line contains two integers, _n_ and _p_ (1 ≤ _n_ ≤ 100 000, 1 ≤ _p_ ≤ 109) — the number of devices and the power of the charger.\n\nThis is followed by _n_ lines which contain two integers each. Line _i_ contains the integers _a__i_ and _b__i_ (1 ≤ _a__i_, _b__i_ ≤ 100 000) — the power of the device and the amount of power stored in the device in the beginning."},{"iden":"output","content":"If you can use the devices indefinitely, print _\\-1_. Otherwise, print the maximum amount of time before any one device hits 0 power.\n\nYour answer will be considered correct if its absolute or relative error does not exceed 10 - 4.\n\nNamely, let's assume that your answer is _a_ and the answer of the jury is _b_. The checker program will consider your answer correct if ."},{"iden":"examples","content":"Input\n\n2 1\n2 2\n2 1000\n\nOutput\n\n2.0000000000\n\nInput\n\n1 100\n1 1\n\nOutput\n\n\\-1\n\nInput\n\n3 5\n4 3\n5 2\n6 1\n\nOutput\n\n0.5000000000"},{"iden":"note","content":"In sample test 1, you can charge the first device for the entire time until it hits zero power. The second device has enough power to last this time without being charged.\n\nIn sample test 2, you can use the device indefinitely.\n\nIn sample test 3, we can charge the third device for 2 / 5 of a second, then switch to charge the second device for a 1 / 10 of a second."}],"translated_statement":null,"sample_group":[],"show_order":[],"formal_statement":null,"simple_statement":null,"has_page_source":false}