b = gets.to_i
n = gets.to_i
c = STDIN.map(&:to_i)
c_uniq = c.uniq.push((c.inject(&:+) + b) / n)
ans = []
c_uniq.each{|standard|
    give = b
    sum = 0
    c.each{|candy|
        tmp = candy - standard
        give += tmp
        sum += tmp.abs
    }
    if give >= 0
        ans.push(sum)
    end
    }
p ans.min