import std.algorithm, std.array, std.container, std.range, std.bitmanip;
import std.numeric, std.math, std.bigint, std.random, core.bitop;
import std.string, std.regex, std.conv, std.stdio, std.typecons;

void main()
{
  auto b = readln.chomp.to!int;
  auto n = readln.chomp.to!size_t;
  auto ci = iota(n).map!(_ => readln.chomp.to!int).array;

  auto maxR = (ci.sum + b) / n;

  int calc(int r) { return ci.map!(c => (c - r).abs).sum; }

  auto s = iota(maxR + 1)
    .map!(r => calc((r + 1).to!int) - calc(r.to!int))
    .assumeSorted.lowerBound(0);

  writeln(calc(s.length.to!int));
}