A circular plasmid has three different but unique restriction sites for enzymes $‘\text{a'}, ‘\text{b'}$ and $‘\text{c'}.$ When enzymes $‘\text{a'}$ and $‘\text{b'}$ are used together, two fragments of equal size are generated. Enzymes $‘\text{c'}$ creates fragments of equal size only from one of the fragments generated by those cleaved by  $‘\text{a'}$ and $‘\text{b'}.$ The plasmid is treated with a mixture of $‘\text{a'}, ‘\text{b'}$ and $‘\text{c'}$ and analysed by agarose gel electrophoresis. The number of bands observed in the gel is _________.