Arrange the following ligand in the order of increasing field strength.

$\begin{array}{ccccc}{\mathrm{H}}_2\mathrm{O}& \mathrm{CO}& {\mathrm{NH}}_3& {\mathrm{I}}^{-}& {\mathrm{F}}^{-}\\ \mathrm{I}& \mathrm{II}& \mathrm{III}& \mathrm{IV}& \mathrm{V}\end{array}$