Complex sentence: Ukraine is a regular participant in the Olympic Games, both summer and winter and is successful on the international arena, country's top achievent at the olympics was at 1996 Summer Olympics, when they came 9th.
Split into simpler sentences: Ukraine is a regular participant in both summer and winter Olympic Games and is successful on the international arena. The country's top achievement at the Olympics to date was at the 1996 Summer Olympics, when they came 9th.