# Connection of cities

Five cities $$P,Q,R,S,T$$ are connected by different modes of transport as follows

• $$P$$ and $$Q$$ connected by boat as well as rail.
• $$S$$ and $$R$$ connected by bus and boat.
• $$Q$$ and $$T$$ connected by air only.
• $$P$$ and $$R$$ connected by boat only.
• $$T$$ and $$R$$ connected by rail and bus.

If a person visits each of the places starting from $$P$$ and gets back to $$P,$$ which of the following places must he visit twice?

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