#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <iomanip>
#include <assert.h>
#include <array>
#include <cstdio>
#include <cstring>
#include <random>
#include <functional>
#include <numeric>
#include <bitset>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(c) (c).begin(), (c).end()
#define zero(a) memset(a, 0, sizeof a)
#define minus(a) memset(a, -1, sizeof a)
#define minimize(a, x) a = std::min(a, x)
#define maximize(a, x) a = std::max(a, x)

using ll  = long long;
ll const inf = 2 * 1e9 + 10;

ll B, N;
vector<ll> C;

ll check(ll const x) {
  ll b = B;
  ll res = 0;
  rep(i, N) {
    if(C[i] < x) {
      b -= x - C[i];
      if(b < 0) { return inf; }
    }
    else {
      b += C[i] - x;
    }
    res += abs(C[i] - x);
  }
  return res;
}

int main() {

  cin >> B >> N;
  C.resize(N);
  rep(i, N) cin >> C[i];
  sort(C.rbegin(), C.rend());
  ll l = -1, r = 1e9 * 2 + 2;
  rep(_, 1000) {
//    ll diff = (r - l) / 3;
//    ll lm = l + diff, rm = r - diff;
    ll lm = (2 * l + r) / 3;
    ll rm = (l + 2 * r) / 3;
    auto rlm = check(lm);
    auto rrm = check(rm);
    if(rlm <= rrm) {
      r = rm;
    }
    else {
      l = lm;
    }
  }

  ll res = inf; REP(i, l-200, l+200) { minimize(res, check(i)); }
  cout << res << endl;

  return 0;
}