module Vailid

# File lib/vailid.rb, line 7
def self.valid?(*args)
        if (args.length == 1)
                validator(args.first)
        else
                false
        end
end

# File lib/vailid.rb, line 15
def self.validator(str)
        return false unless (str != nil)
        str=str.to_s
        return false unless (str.length <= LENGTH)
        return false unless (str.to_i != 0)
        while(str.length < LENGTH)
                str="0".concat(str)
        end
        sum=0
        for i in 0..(LENGTH-1)
                if (i%2==0)
                        sum+=       str[i].to_i
                else
                        temp= 2*str[i].to_i
                        (temp=temp/10 + temp%10) unless (temp<10)
                        sum+=temp
                end
        end
        (sum%10==0)? true : false
end