#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

int main() {
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(cin.failbit);

  auto msb = [&](ll x)->int {
    if (x == 0) return 0;
    return __lg(x) + 1;
  };

  ll n;
  int m;
  cin >> n >> m;
  vi p(m);
  vector<vector<ll>> levels(64);
  for (auto& x : p) {
    cin >> x, x--;
    levels[msb(x)].push_back(x);
  }
  map<ll, array<int, 2>> dp;
  for (auto& x : p) {
    dp[x] = {1, 0};
  }
  for (auto x: p) {
    ll up = ((1LL<<msb(x)) - x - 1) + (1LL<<msb(x));
    if (up < n && !dp.count(up)) {
      levels[msb(up)].push_back(up);
      dp[up] = {0, 1};
    }
  }

  for (int j = sz(levels) - 1; j > 0; j--) {
    if (levels[j].empty()) continue;
    auto& level = levels[j];
    for (auto& x : level) {
      int bit = j - 1;
      ll to = (1LL<<bit) - 1 - (x - (1LL<<bit));
      if (!dp.count(to)) {
        levels[msb(to)].push_back(to);
        dp[to] = {0, 1};
      }

      array<int, 2> ndp;
      ndp[0] = min(dp[to][0] + dp[x][0], dp[to][1] + dp[x][1] + 1);
      ndp[1] = min(dp[to][1] + dp[x][1], dp[to][0] + dp[x][0] + 1);
      dp[to] = ndp;
    }
  }

  cout << min(dp[0][0], dp[0][1]) << '\n';
}