If you have wrong anwer at test 6, try this test:
4 3
3 4 5

Correct answer: 1
Because at ith minute, there is only a[i] cars come to the traffic jam. Good luck to you!

thanks :)

Thank you very much! :-D

I have ansver 1. But WA6........

thank you

thanks buddy :)
but how did you get the test case and the correct answer?

Can u help? I have wrong answer(test 10).