of;
Mathematics,;
University;
of;
Biatystok;
Akademicka;
2,;
15-267;
Biatystok,;
Poland;
of;
Mathematics;
and;
Information;
Science,;
Warsaw;
University;
of;
Technology,;
ul.Koszykowa;
75,;
00-662;
Warsaw,;
Instituteof;
Mathematics,;
University;
of;
Biatystok;
Akademieka;
2,;
15-267;
Biatystok,;
Poland.;