#include <iostream>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <utility>
#include <cstdio>

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define DEBUG(x) cout<<#x<<": "<<x<<endl

using namespace std;

typedef pair<int,int> P;
typedef long long int LL;
typedef pair<LL,LL> LP;


int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	LL B,N;
	cin>>B;
	cin>>N;
	vector<LL> C(N);
	REP(i,N)	cin>>C[i];
	sort(ALL(C));
	LL p=C[N/2];
	//DEBUG(p);
	LL ans;
	LL tm=0;
	REP(i,N){
		tm+=p-C[i];
	}
	//DEBUG(tm);
	if(tm>B){
		LL l=0,r=p;
		while(l+1<r){
			//cout<<l<<' '<<r<<endl;
			LL m=(l+r)/2;
			LL t=0;
			REP(i,N)	t+=m-C[i];
			//DEBUG(t);
			if(t<=B){
				l=m;
			}else{
				r=m;
			}
		}
		//cout<<l<<' '<<r<<endl;
		p=l;
	}
	ans=0;
	//DEBUG(p);
	REP(i,N)	ans+=abs(p-C[i]);
	cout<<ans<<endl;
	return 0;
}