P0009. Solvent economics P91432


Statement
 

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Being S=s1, s2, …, sn a sequence of integers. Its derivative is the sequence

S′=(s2s1),   (s3s2),   …  ,   (snsn−1)

and its second derivativeS″ is the derivative of S′.

A sequence is called strictly increasing if all the elements of its derivative are strictly greater than zero. A sequence is called strictly convex if all the elements of its second derivative are strictly greater than zero.

Stock indices (as the IBEX 35 or the NASDAQ) measure economies, and their evolution along the time can be seen like a sequence of integers. In this context, it is said that an economy is solvent if its sequence is strictly increasing (the wealth grows) or strictly convex (perhaps it does not grow but it tends to the growth).

For instance, S=1,3,10,12 reflects a solvent economy because is strictly increasing, although it is not strictly convex (S′=2,7,2;  S″=5,−5). S=3,−2,−4,−1,5 reflects a solvent economy also, because is strictly convex, although it is not strictly increasing (S′=−5,−2,3,6;   S″=3,5,3).

Your task is to write a program that reads a sequence of, at least, three integers, and prints if they reflect a solvent economy or not.

Input

The input is a sequence of three or more integers.

Output

Your program must print textttsolvent economy” or “not solvent economy”, depending on the result, in a line.

Public test cases
  • Input

    1 3 10 12
    

    Output

    solvent economy
    
  • Input

    3 -2 -4 -1 5
    

    Output

    solvent economy
    
  • Input

    5 3 1
    

    Output

    not solvent economy
    
  • Input

    -4 -3 -1
    

    Output

    solvent economy
    
  • Input

    2 3 0 1
    

    Output

    not solvent economy
    
  • Information
    Author
    Professorat de P1
    Language
    English
    Translator
    Carlos Molina
    Original language
    Catalan
    Other languages
    Catalan
    Official solutions
    C++
    User solutions
    C++