#include<bits/stdc++.h>
using namespace std;
const int N=1919810;
typedef long long ll;
typedef pair<ll,ll> PII;
ll n,m;
ll a[N],b[N];
vector<ll> e[100];

map<ll,int> mp;
int main(){
    cin>>n>>m;
    for(int i=1;i<=m;i++) scanf("%lld",&a[i]);
    vector<ll> v;
    for(int i=1;i<=m;i++) v.push_back(a[i]);
    sort(v.begin(),v.end());
    map<ll,int> mp;
    for(auto j:v) mp[j]=1;
    ll ans=0;
    ll val=0;
    while((1ll<<val)<n) val++;
    for(int i=val;i>0;i--){
        ll tot=(1ll<<i);
        while(v.size()&&v.back()>tot) v.pop_back();
        vector<ll> vv;
        for(auto j:v){
            if(mp[j]!=2) mp[j]=1;
        }
        set<ll> se;
        for(auto j:v){
            ll nw=tot+1-j;
            se.insert(min(j,nw));
        }
        for(auto j:se){
            ll nw=tot+1-j;
                // cout<<j<<" "<<nw<<endl;
                if(mp[j]==2){
                    mp[j]=mp[nw];
                }else{
                    if(mp[nw]!=mp[j]){
                        mp[j]=2;
                        ans++;
                    }
                }
            
        }
        for(auto [x,y]:mp) if(y==1) vv.push_back(x);
        v=vv;
    }
    cout<<ans<<endl;

}