Traffic Lights
View as PDFJim-Bob lives in a strange city where the streets don't necessarily run
NS or EW. Instead the  
 streets run seemingly
at random, sometimes crossing over each other by bridges, and
intersecting with one another at exactly 
 
intersections. Each intersection consists of some streets coming
together, as well as a traffic light.
Street  starts at intersection 
 
, and
ends at a different intersection 
 
, going
through no other intersections in between. It takes 
 minutes to travel down street 
 (this number is
derived from the length, the average pothole size, and the amount of
roadkill). Each road can be travelled in either direction in the same
amount of time.
The traffic lights in this city are also strange. First of all, each one
only alternates between green and red. Each light also cycles through
these colours at a different rate – the traffic light located at
intersection  stays green for 
 
minutes, then stays red for 
 
 minutes,
then goes back to green, and so on.
Jim-Bob always obeys the law, and will never run a red light. If he arrives at an intersection while the light is green, he can pass right through it. Otherwise, he must wait there until the light turns green. If he gets to an intersection just as the traffic light is turning red, he must wait. It takes no time to drive through an intersection, so the light will never turn red on him as he drives through.
Jim-Bob starts at his house, also known as intersection . As soon as
he leaves his house, all the traffic lights turn green, starting their
green-red-green cycle. He wishes to drive to Billy-Bob's house (which is
right at intersection 
) as fast as possible. Neither the starting nor
the finishing intersection have traffic lights, so their 
 and 
will be given as 
. Find the minimum number of minutes Jim-Bob can take
to drive from his house to Billy-Bob's.
Input Specification
 integers – 
 and 
.
The next  lines contain 
 integers each – 
, 
, and 
.
The next  lines contain 
 integers each – 
, and 
.
Output Specification
A single integer – the minimum number of minutes it takes to drive from Jim-Bob's house to Billy-Bob's. It will always be possible to do this.
Sample Input
7 6
1 2 4
1 3 1
3 5 2
2 4 2
2 5 6
5 4 2
5 6 10
0 0
5 5
1 20
2 5
10 2
0 0
Sample Output
19
Explanation
The city looks something like this (Jim-Bob's best route is shown in red):
Jim-Bob can drive to intersection  (
 min), drive on to intersection 
(
 min), wait for the green light (
 min), drive down to intersection 
(
 min), and finally drive to Billy-Bob's house (
 min). This is a
total of 
 minutes.
Note: The traffic light at intersection  only stays green for 
 minute,
which means that Jim-Bob would just miss it if he drove directly there.
On the other hand, he makes the green lights as intersections 
 and 
just in time, as they turn red 
 minute after he passes.
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