open System
open FSharp.Collections


let km2m (x:int) = (float x) / 3.6
let m2km x = x*3.6
let secondsToArrive  (distance:int) (speed:float)  =
    eprintfn "distancia : %i , velocidad : %f" distance speed
    (float distance)/speed
let checkGreenLight (duration:int) (arrive:float)  =
    eprintfn "llegada : %f , duracion : %i" arrive duration
    eprintfn "llegada entre duracion: %f"  (arrive/(float duration))
    (int( arrive/(float duration)) % 2) = 0
let mutable SuccesChekers = []
let addToList (listan) (element) = element::listan

let speed = int(Console.In.ReadLine())
let lightCount = int(Console.In.ReadLine())



for i in 0 .. lightCount - 1 do
    let token = (Console.In.ReadLine()).Split [|' '|]
    let distance = int(token.[0])
    let duration = int(token.[1])
    let currentSeconds = secondsToArrive distance
    let currentGreen =  checkGreenLight duration
    let succesCheck = km2m >> currentSeconds >>  currentGreen
    SuccesChekers <- addToList SuccesChekers succesCheck
    ()
let mutable maxSpeed =0
let checkGivenSpeed speed (listOfChecks: (int->bool)list) =
    List.forall(fun elem-> elem speed ) listOfChecks

let speeds= Seq.sortDescending (seq { 0 .. speed })

eprintfn " Para 60 el resultado es: %b " (checkGivenSpeed speed SuccesChekers)
let result=Seq.find (fun elem-> (eprintfn "%i" elem );  checkGivenSpeed elem SuccesChekers) speeds



(* Write an action using printfn *)
(* To debug: eprintfn "Debug message" *)

printfn  "%i" result