// Sieve of Eratosthenes

fn init_array(len: i64) -> [i64] {
    let nums = [0; len];
    let mut i = 0;
    while (i < nums.length) {
        nums[i] = i;
        i=i+1;
    }
    nums
}

fn sieve_all(nums: [i64]) -> () {
    let mut i = 2;
    while (i < nums.length) {
        sieve(nums, i);
        i=i+1; 
    }
}

fn sieve(nums: [i64], n: i64) -> () {
    let i = 2*n;
    while (i < nums.length) {
        nums[i] = 0;
        i=i+n;
    }
}

fn print_primes(nums: [i64]) -> () {
    print("Primes less than ");
    printi64(nums.length);
    print(": ");
    let mut i = 2;
    while (i < nums.length) {
        if (nums[i] != 0) {
            printi64(nums[i]);
            print(" ");
        }
        i=i+1;
    }
    println("");
}

fn main(args: [String]) -> () {
    if (args.length != 1) {
        println("Unspecified numsber.");
        return ()
    }
    println("");
    let n = parsei64(args[0], 0);
    if (n <= 0) {
        println("Invalid array length");
        return ()
    }
    let nums = init_array(n);
    sieve_all(nums);
    print_primes(nums);
}