Pairs of a sequence (1) P85480


Statement
 

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Write a program that reads sequences of natural numbers, and for each one tells if it has two elements such that their sum is a prime number.

Input

Input consists of several sequences, each one in a line. Each sequence consists of a natural number n, followed by n natural numbers x1, …, xn.

Output

For each input sequence, print “yes” or “no” depending on if it is possible to find two elements xi and xj (with ij) such that xi + xj is a prime number.

Observation

Using arrays, it is possible to precompute which numbers are prime and which are not up to a certain maximum. In this exercice it is not possible because we do not know any maximum, and it is not necessary for efficiency reasons because all the numbers are small enough.

Public test cases
  • Input

    6   3 5 7 15 13 1
    2   0 2
    

    Output

    no
    yes
    
  • Information
    Author
    Salvador Roura
    Language
    English
    Translator
    Carlos Molina
    Original language
    Catalan
    Other languages
    Catalan
    Official solutions
    C++
    User solutions
    C++