| Турнир Архимеда 2021 |
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Passing by your old acquaintances, the philologist Fedot and the biologist Bogdan, you overheard that they were fiercely arguing about something related to mathematics. The topic of their argument was whether any digit can be the starting digit of a square of a prime number.
Let us remind you (mainly, of course, Fedot and Bogdan) that a prime number is an integer greater than one that has no natural divisors other than itself and one. And also, let us remind you that the square of a number $$$n$$$ is defined as $$$n^2 = n \cdot n$$$ — the product of a number with itself.
As a follower of technical sciences, you decided to intervene in the dispute, fully aware that any mathematical statement you make will require a clear proof even to a philologist and a biologist. Fedot and Bogdan gave you a digit $$$c$$$, and now you have to find a square of a prime number that starts with it, or inform them that it does not exist.
The input consists of a single line containing one character — the digit $$$c$$$, which is also a number from zero to nine inclusive.
If there exists a prime number $$$p$$$ such that $$$N=p^2$$$ starts with the digit $$$c$$$, then output such number $$$N$$$. It should satisfy the inequality $$$1 \le N \le 10^{18}-1$$$ (in other words, $$$N$$$ should have from 1 to 18 digits inclusive).
If such prime number does not exist, output "No number". If there are multiple possible answers, output any.
0
No number
4
49
9
9
Natural numbers do not start with zero, so there is no answer in the first example.
In the second and third examples, many other numbers are also valid answers, for example, $$$4=2^2$$$ and $$$961=31^2$$$.
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