# 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 / cs.length
if(avg-avg.to_i>0.5 && (total-avg.to_i*cs.length)<=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