activity of 11 days = 11 Morn(M) and 11 evenings(E)
i.e. walk 6 M AND badminton 5 Evenings. This leaves 5 M AND 6 E.
walk 5M and Badminton 6 E. this leaves 6M and 5E- no activity.
considering first posssibilty leads nowhere.
But if we consider 2nd possibility;
now, 11 M and 10 E did nothing, including the activity days.
this leaves full day of no activity - 5 M and 5 E= 5 days
the total days= 11+5days=16 days.