#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
// constexpr int MOD = 1000000007;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  constexpr int L = 100000;
  int l, n; cin >> l >> n;
  vector<int> x(n + 2, 0); FOR(i, 1, n + 1) cin >> x[i];
  vector dp(n + 2, vector(2, bitset<L + 1>()));
  dp[0][0].set(0);
  REP(i, n + 1) FOR(k, i + 1, n + 2) {
    dp[k][1] |= dp[i][0] << (x[k] - x[i]);
    dp[k][0] |= dp[i][1];
  }
  int ans = INF;
  REP(i, l + 1) {
    if (dp[n + 1][0][i]) chmin(ans, abs(i * 2 - l));
  }
  cout << ans << '\n';
  return 0;
}