Three villages \(P, Q,\) and \(R\) are located in such a way that the distances are \(PQ=13\) km, \(QR=14\) km, and \(RP=15\) km (see figure). A straight road joins \(Q\) and \(R\). It is proposed to connect \(P\) to this road \(QR\) by constructing another road. What is the minimum possible length (in km) of this connecting road?