#include <iostream>
#include <windows.h>

using namespace std;

unsigned N, count = 0;

void placeQueen( unsigned col, unsigned ls, unsigned ns, unsigned rs )
{
    if ( col == N )
    {
        ++count;
        return;
    }

    unsigned row = ls & ns & rs;
    __asm
    {
        stc
        rcl ls, 1
        stc
        rcr rs, 1
    }

    if ( !col ) row >>= N/2;
    while ( row )
    {
        unsigned current = row;
        row &= row - 1;
        current ^= row;
        if ( !( col || row ) && ( N & 1 ) ) count <<= 1;
        placeQueen( col + 1, ls & ~( current << 1 ), ns & ~current, rs & ~( current >> 1 ) );
    }
}

void main( )
{
    cout << "Enter number of queens (1..32): ";
    cin >> N;
    cout << "Placing " << N << " queens...\n";

    unsigned value = 0;
    for ( unsigned k = 0; k < N; ++k ) value |= 1 << k;

    DWORD time0 = GetTickCount();
    placeQueen( 0, 0xFFFFFFFF, value, 0xFFFFFFFF );
    if ( !( N & 1 ) ) count <<= 1;
    DWORD time1 = GetTickCount();

    cout << count << " placings at all.\n" << time1 - time0 << " ms passed.\n";
}