#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
#define dame { puts("-1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll b, n;
    cin >> b >> n;
    ll c[n];
    ll sum = b;
    rep(i,n){
        cin >> c[i];
        sum += c[i];
    }
    sort(c,c+n);
    ll ans = 1001001001001;
    rep(i,n){
        if(c[i] * n > sum)continue;
        ll tmp = 0;
        rep(j,n)tmp += abs(c[j] - c[i]);
        ans = min(ans, tmp);
    }
    ll tmp = 0;
    ll cc = sum / n;
    rep(j,n)tmp += abs(c[j] - cc);
    ans = min(ans, tmp);
    cout << ans << endl;
    return 0;
}