Hello , I have a question and it's how should we find the number of groups of -1s in a sequence of 1s and -1s ...?

For example if we have the sequence of length n that n=5 like this :

-1 , 1 , -1 , -1 , 1

In this example we have two groups first group contains the first number and the second group contains the 3rd and 4th number .

Given N and the sequence can you please tell me the number of groups of -1s that are after each other ?

Hi , I have been thinking a lot but I haven't had any good idea about this , so I want your help : We are given an integer N and N strings , how could we find the longest common substring of them and the length of longest common substring of them ?

I was thinking about only div 2 contests and I decided to NOT register for them because some of div1 users do something shameful and make a new account and participate in div2 contests ...

Like these two accounts :

• JuanMata

• smart_lovely_JuanMata

It's a long time I have been in codeforces and solving problems .... I can solve the A problems very quickly ( at most 10 minutes ) But how much I try I cannot solve the B problem ... What should I do ? Notice : I'm 15 and I'm a beginner ..