1007.素數對猜想

bool sushu(int n)
{
    for (int i = 2; i <= sqrt(n);++i)
    {
        if (!(n%i))
        {
            return 0;
        }
    }
    return 1;
}


int _tmain(int argc, _TCHAR* argv[])
{
    int num;
    cin >> num;
    int cnt = 0;
    int s1 = 2, s2 = 3;
    for (int i = 5; i < num + 1;i+=2)
    {
        if (sushu(i))
        {
            s1 = s2;
            s2 = i;
            if (s2-s1 ==2)
            {
                ++cnt;
            }
        }
    }
    cout << cnt << endl;
    return 0;
}