class DifferenceAverage
    attr_reader :n, :k, :numbers

    def initialize(n: 0, k: 0, numbers: [])
        @n, @k, @numbers = n, k, numbers
    end

    def cause
        begin
            @n = Integer(gets.chomp)
            @k = Integer(gets.chomp)
            @numbers = @n.times.map { Integer(gets.chomp) }
        rescue
            
        end
    end

    def result
        @numbers = @numbers.sort
        puts @numbers[-1] - @numbers[0]
    end

    def run
        cause
        result
    end
end

if $0 == __FILE__
    DifferenceAverage.new.run
end