| The things you should know: 
 | 
 This problemset has been prepared by the ProblemSetters of the Competitive Programming Network. Should you want to know more about us, or collaborate by writing problems with us, please visit our official web page, visit our facebook fanpage and follow us on twitter (@RedProgramacion). Also feel free to contact us at mail @ redprogramacioncompetitiva.com.
        This problemset has been prepared by the ProblemSetters of the Competitive Programming Network. Should you want to know more about us, or collaborate by writing problems with us, please visit our official web page, visit our facebook fanpage and follow us on twitter (@RedProgramacion). Also feel free to contact us at mail @ redprogramacioncompetitiva.com.
        
        