Interesting problem

[kate]

Maximum two people at time can cross one bridge. During the night the bridge is dark, there are no lights, and it can be crossed only with a flashlight. At the one end of the bridge there are 4 people with one flashlight. The first person can cross the bridge for 1 minute, the second - for 2 minutes, the third - for 5 minutes and the last one - for 7 minutes. What is the least time in which these four people can pass the bridge?