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There are 5 persons standing on a side of tunnel.
A, B, C, D, E
10, 30, 15, 20, 29 minutes to cross tunnel respectively.
You are giving them instructions to cross.
Problem is at a time 2 person can cross tunnel with flash light.
After crossing one person should come back with flash light because its only one.
How you will manage them so that in a minimum time they can cross tunnel?