The values of conductivity of some materials at 298.15 K in S m$$^{-1}$$ are $$2.1 \times 10^3$$, $$1.0 \times 10^{-16}$$, $$1.2 \times 10$$, $$3.91$$, $$1.5 \times 10^{-2}$$, $$1 \times 10^{-7}$$, $$1.0 \times 10^3$$. The number of conductors among the materials is