Four people A, B, C and D take 1, 2, 5 and 10 minutes respectively to cross a bridge at night. Only one torch is available, at most two peo…

Four people A, B, C and D take 1, 2, 5 and 10 minutes respectively to cross a bridge at night. Only one torch is available, at most two people can cross at a time and they must walk at the slower person's speed; the torch has to be carried back for the others. What is the minimum total time for all four to cross?