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?