Today there are appx 5,000 people w/Udin = Юдин surname living throughout Ukraine (UA). Closer transliteration would be Y(J)udyn.

177 currently reside in Kyiv, the capital. Another 25 + live in other towns in the Kyiv oblast/region.
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Tranliterational (sounds-like) variants of Mandel/Mendel surname found in Kyiv today:
Мандельбаум = Mandelbaum
Мандельблат = Mandelblat
Мандель = Mandel
Мандельгейм = Mandelgame
Мендаленко =Mendalenko
Мендеграл = Mendelgral
Менделевич = Mendelevych
Менделеєв = Mendeleyev
Менделєєв = Mendelyeyev
Менделенко = Mendelenko
Менделуца = Mendelutza
Мендель = Mendel
Мендельсон = Mendelson