#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;


ll B;
int N;
vll C;

void solve(){
    ll lim = accumulate(all(C), B) / N;
    sort(all(C));

    ll ans = LLONG_MAX;

    each(a, C){
        if(a > lim)break;
        ll val = 0;
        each(b, C){
            val += abs(a - b);
        }
        smin(ans, val);
    }
    
    ll val = 0;
    each(b, C)val += abs(lim - b);
    smin(ans, val);

    cout << ans << endl;
}

int main(){
    while(cin >> B >> N){
        C.resize(N);
        rep(i, N)scanf("%lld", &C[i]);
        solve();
    }
}