A river of width L is flowing with uniform velocity $V_0$. A swimmer jumps in water at point A with speed of $V_0$  relative to water. Swimmer crosses the river in such a way that the resultant velocity of swimmer is always perpendicular to the line joining swimmer and point C.  Point B is directly opposite to point A and point A, B and C are collinear. If swimmer crosses the river in time $T_0;$  then the value of $T_0$  will be?  ( $\underset{ }{\overset{ }{\int }}\sec \theta d\theta =\ln (\sec \theta +\tan \theta )+C$)