unsigned squares_above( unsigned n, unsigned m, unsigned min )
{
    if ( n == 0 )
        return 1;
    if ( m == 0 )
        return 0;

    unsigned c = 0;
    for ( int i = min; i * i <= n; ++i )
    {
        c += squares_above( n - i * i, m - 1, i );
    }
    return c;
}

unsigned squares( unsigned n, unsigned m )
{
    return squares_above( n, m, 1 );
}