Let's play dice! The traditional die is a cube

[qerties]

Hello, anyone can help with this problem?
Let's play dice! The traditional die is a cube. Each of its six faces shows a different number of dots from 1 to 6. Dice are used to produce results from 1 through 6. When a die is thrown (or rolled) and the die comes to rest, the face of the die that is uppermost provides the value of the throw. If an unbiased die is thrown, each value from 1 to 6 is equally likely.

Your programming task is related to the analysis of sequences produced by rolling a die.

Create a program named Dice to solve the following exercises. The input of the program is a so-called trial, i.e. a sequence of the rolled results. This input must be read from the standard input. The first line of the input contains a single integer N, indicating the number of throws \left(1\le N\:\le1000000\right). The second line of the input contains exactly N characters, each character is a digit from 1 to 6. For example, the input can be as follows:
8
32646135
Exercises
Exercise 1
How many times did it occur in the trial, that exactly two 6s were rolled after each other? For example, in sequence 56611166626634416 it occurred twice, that exactly two 6s were thrown after each other.

Exercise 2
Find the length of the longest subsequence of successive rolls, in which the value 6 does not occur. (This number can be zero, if only 6s were thrown.) For example, in the trial 66423612345654 the longest subsequence of successive rolls in which the value 6 does not occur is 12345. Its length is 5.

Exercise 3
We shall call a sequence of successive rolls in the trial a lucky series, if the sequence contains only 5s and 6s. For example 6556665 is a lucky series, with a length of 7.
Find out, which is the most frequent length for lucky series. If there are more than one "most frequent" lucky series lengths, print the longest. If there are no lucky series in the trial, print zero.

Be aware. We are not interested in the most frequent lucky series. The four lucky series 656, 555, 556 and 666 are equivalent for us, all of them are lucky series of length three. We are looking for the most frequent length of lucky series.

For example, in trial 5533661656, the series 656 is the longest lucky series. But there is only one lucky series of lenght three in the trial. 55 and 66 are also lucky series. This is why the correct answer is 2. In trial 456116513656124566 both the lucky series with length of 2 and 3 occur twice, there is a tie between them. Now the length of the longest (that is 3) should be printed. Examples example1 and example2 are aimed to make this situation clear.

[seeplus]

What help do you want? What attempt(s) have you made so far? What don't you understand? What is the issue? have you got the code to obtain the input? Have you attempted Exercise 1? Post your current code.

[jonnin]

exercise 1 example is weird.
*exactly two* means it happened once, as the second one is 3 which is not exactly 2.
or you can read it another way, it happens 3 times, the first one, then 666 is (66)6 and 6(66). Its hard to translate the english words into any scenario where there are only 2; its either worded wrong or the example is bad.

because most classroom books and sources do not give you much: take a look at this site's sample code and explains on the <random> header. that will help you generate the dice rolls easily. From there it is just counting what you got and doing the work.