def score(n, k)
    return 50 * n + ((50 * n) / (0.8 + 0.2 * k)).floor
end

n, k = STDIN.gets.chomp.split.map{|x| Integer(x)}
if n >= 1 && n <= 6 && k >= 1 && k <= 1000
    puts score(n, k)
end