projecteuler 18

#my try on https://projecteuler.net/problem=18

#error:
#/home/x3nu/Dev/euler/problem18.rb:12:in `block in <main>': undefined method `>' for nil:NilClass (NoMethodError)
#from /home/x3nu/Dev/euler/problem18.rb:5:in `each_line'
#from /home/x3nu/Dev/euler/problem18.rb:5:in `<main>'
#75
#blaaaaaa
#[Finished in 0.1s with exit code 1]


position = 0
sum = 75
array = []

File.open("18.txt", "r").each_line do |line|
    puts line
    array = line.split(",").map { |s| s.to_i }
    posA = position
    posB = position + 1
    if array[posB] != false
        puts "blaaaaaa"
        if array[posB] > array[posA]
            sum += array[posB]
            position = posB
        else
            sum += array[posA]
            position = posA
        end
    else
        sum += array[posA]
        position = posA
    end
end
puts position
puts sum