Simplify the following text for a Grade 9 native English-speaking person.
Original: In Russian literature and informal documents the `` Saint '' ( Ð Ð Ð 1\/2 Ð Ñ - ) is usually omitted , leaving Petersburg ( Ð Ð Ñ Ð Ñ Ð Ñ Ñ Ð , Peterburg ) .
Simplified: Saint Petersburg ( Sankt-Peterburg \/ Ð Ð Ð 1\/2 Ð Ñ - Ð Ð Ñ Ð Ñ Ð Ñ Ñ Ð ) is a Russian city in northwestern Russia on the Gulf of Finland of the Baltic Sea .