UVa 10168 - Summation of Four Primes

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS 1
#endif

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

const int maxVal = 10e7;
bool sieve[maxVal];

int main()
{
    // Load sieve array.
    sieve[0] = true;
    sieve[1] = true;

    for (int i = 2; i*i <= maxVal; i++)
        if (!sieve[i])
            for (int j = i*2; j < maxVal; j += i)
                sieve[j] = true;

    int n;

    while (scanf("%d", &n) != EOF)
    {
        if (n < 8)
            cout << "Impossible.\n";
        else
        {
            int remainder;

            if (n % 2 == 0)
            {
                cout << "2 2 ";
                remainder = n - 4;
            }
            else
            {
                cout << "2 3 ";
                remainder = n - 5;
            }

            for (int i = 2; i < remainder; i++)
            {
                int rmi = remainder - i;
                if (!sieve[i] && !sieve[rmi])
                {
                    cout << i << " " << rmi << "\n";
                    break;
                }
            }
        }
    }

    return 0;
}