Four pieces of wooden sticks P, Q, R and S are placed along the length of a scale(as shown in the figure). Arrange P, Q, R and S in ascending order of their lengths.
rllI|IIIIIIIII|IIlTIII]IlI'III|III1IIII|IIIIIIIII|IIITIII|IIIIrII!Il'III|IIITIII]IIITI|I||I|T|I|||I|TIII|III|I|I|I|IIII|IIII|I