Eulerian and Hamiltonian Graphs · Medium problem

Six landmasses are joined by bridges: a hub $C$ has one bridge each to $A$, $B$, and $D$, plus one bridge to $E$; and $E$ has two SEPARATE bridges to $F$ (so $E$–$F$ is doubled). What is the minimum number of new bridges that must be added so that SOME walk crosses every bridge exactly once (not necessarily returning to its start)?