optimize this ruby code
So this code will count the total number of pairs of numbers whose difference is K. it is naive method and I need to optimize it. suggestions?

    test = $stdin.readlines 

    input = test[0].split(" ")

    numbers = test[1].split(" ")

    N = input[0]
    K = input[1]

    count = 0

    for i in numbers
       current = i.to_i
       numbers.shift
       for j in numbers
           difference = (j.to_i - current).abs
           if (difference == K)
               count += 1
           end
       end
    end

    puts count
optimize this ruby code
===

So this code will count the total number of pairs of numbers whose difference is K. it is naive method and I need to optimize it. suggestions?

    test = $stdin.readlines 

    input = test[0].split(" ")

    numbers = test[1].split(" ")

    N = input[0]
    K = input[1]

    count = 0

    for i in numbers
       current = i.to_i
       numbers.shift
       for j in numbers
           difference = (j.to_i - current).abs
           if (difference == K)
               count += 1
           end
       end
    end

    puts count