open System.Collections.Generic
// open System.Diagnostics

let sieveOfEratosthenes n =
    let isPrime = Array.create n true
    let primes = new List<int>()
    Array.set isPrime 0 false
    Array.set isPrime 1 false
    for i = 2 to n - 1 do
        if isPrime.[i] then
            primes.Add(i)
            for j in 2 * i .. i .. n - 1 do
                Array.set isPrime j false
    primes

let () =
    let n = 5000000
    // let stopwatch = Stopwatch.StartNew()
    let primes = sieveOfEratosthenes n
    // stopwatch.Stop()
    // printfn "%.3f ms" stopwatch.Elapsed.TotalMilliseconds
    printfn "%d" 0