# Here your code !
B = gets.to_i
N = gets.to_i
cs = []
N.times{
    c = gets.to_i
    cs.push(c)
}

total = cs.inject(&:+)
avg = total.to_f / cs.length.to_f
if(avg-avg.to_i>0.5 && (avg.to_i+1)*cs.length-total<=B)
    avg = avg.to_i + 1
else
    avg = avg.to_i
end

totaldiff = 0
cs.each{|c|
    diff = (c - avg).abs
    totaldiff += diff
}
puts totaldiff