YoungHee and KwangHee did not meet each other for a long time since they visited
Chung-Poong Resort Center early this year. They’ve never been in this long
time even without talking to each other though they were in a good friendship
since 7th grade in the middle school.  

YoungHee strongly suspected that KwangHee must be doing something which she wanted
to hide.  YoungHee made up her mind to see KwangHee and listen what has turned her
back on the world. So YoungHee uses a Candy that KwangHee loves to eat.

First YoungHee called KwangHee and asked her to come to a certain place.
Actually they are missing each other very much and finally going to meet by running up
against each other till they collide. They are on the same track with a distance 120 m
apart heading towards one another, each at a speed of 5 m/sec.

YoungHee, starting from left to right throws a candy with a speed of 7 m/sec to
KwangHee who is heading from right to left.  As soon as KwangHee catches this candy
she didn’t eat it but threw it back to YoungHee, saying “Hey,  YoungHee,  you eat first!
I’m O.K.”

But YoungHee sent it back to KwangHee and KwangHee did the same again and again
till they collide each other. Just before they collide each other this Candy will be
eaten by either one of them.


Can you imagine how far did this Candy travel in total while being tossed back and forth ???

                                   Your Answer : ______________meters.