Direction: In the following question, the first and the last part of the passage is numbered as 1 and 6. The rest of the passage is split into six parts and numbered as P, Q, R, and S. These four parts are not given in the proper order. Read the sentences and find out which of the four combinations is correct.

S1 Deserts are wild waste stretches of land.
P They are usually covered with sand where little can grow and few can live.
Q There are deserts in many countries.
R The greatest and the most famous of the deserts is the Sahara.
S It covers 35 lakh square miles of Northern Africa.
S6 Crossing a desert has always been a risky adventure.