#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define xx first
#define yy second
#define sci(n) scanf("%d",&n)
#define scii(n,m) scanf("%d%d",&n,&m)
#define sciii(n,m,w) scanf("%d%d%d",&n,&m,&w)
#define scl(n) scanf("%lld",&n)
#define scll(n,m) scanf("%lld%lld",&n,&m)
#define sclll(n,m,w) scanf("%lld%lld%lld",&n,&m,&w)
#define pf(a)   printf("%d\n",a)
#define CASE(a) printf("Case %d:\n",a)
#define dbg(i) printf("yo %lld\n", i)
#define endl '\n'
#define READ  freopen("input.txt","r",stdin)
#define WRITE freopen("output.txt","w",stdout);
#define pi acos(-1)
#define mem(a,b) memset(a,b,sizeof(a))
#define SQR(a) (a)*(a)
#define all(v) v.begin(),v.end()
#define pb push_back
#define pri priority_queue<int>
#define rev_pri priority_queue<int,vector<int>,greater<int> >
#define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define mod 1000000007
#define inf INT_MAX
#define eps 1e-9
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define snuke(c,itr) for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)

using namespace __gnu_pbds;
using namespace std;

int dx[] = {0,1,0,-1,1,1,-1,-1};
int dy[] = {1,0,-1,0,1,-1,-1,1};
//ll ncr(ll n,ll r){
    //if(n==r)return 1;
    //if(r==1)return n;
    //if(dp[n][r]!=-1)return dp[n][r];
    //return dp[n][r]=ncr(n-1,r)+ncr(n-1,r-1);
//}

bool checkbit(int mask,int bit){
    return mask & (1<<bit);
}
int setbit(int mask,int bit){
    return mask | (1<<bit) ;
}
int clearbit(int mask,int bit){
    return mask & ~(1<<bit);
}
int togglebit(int mask,int bit){
    return mask ^ (1<<bit);
}
int topbit(signed t){
	return t==0?-1:31-__builtin_clz(t);
}
int topbit(ll t){
	return t==0?-1:63-__builtin_clzll(t);
}
int botbit(signed a){
	return a==0?32:__builtin_ctz(a);
}
int botbit(ll a){
	return a==0?64:__builtin_ctzll(a);
}
int popcount(signed t){
	return __builtin_popcount(t);
}
int popcount(ll t){
	return __builtin_popcountll(t);
}
bool ispow2(int i){
	return i&&(i&-i)==i;
}

//#define CAPITAL
void yes(bool ex=true){
	#ifdef CAPITAL
	cout<<"YES"<<"\n";
	#else
	cout<<"Yes"<<"\n";
	#endif
	if(ex)exit(0);
}
void no(bool ex=true){
	#ifdef CAPITAL
	cout<<"NO"<<"\n";
	#else
	cout<<"No"<<"\n";
	#endif
	if(ex)exit(0);
}
void possible(bool ex=true){
	#ifdef CAPITAL
	cout<<"POSSIBLE"<<"\n";
	#else
	cout<<"Possible"<<"\n";
	#endif
	if(ex)exit(0);
}
void impossible(bool ex=true){
	#ifdef CAPITAL
	cout<<"IMPOSSIBLE"<<"\n";
	#else
	cout<<"Impossible"<<"\n";
	#endif
	if(ex)exit(0);
}

const ll nax=1000050;
ll n,w,m;
ll ar[nax];
void solve()
{

    ll a,b,c,q,j,l,mx=0,k,i;
    ll hn,hm,gc,sx,sy,ex=1,ey=-1;
    scll(m,n);
    map<ll,ll>mp,exs;
    set<ll>st;
    for(i=1;i<=n;i++)scl(a),exs[a]++;
    for(i=0;i<=101;i++){
        if(exs.count(i)!=0)continue;
        a=abs(i-m);
        if(mp.count(a)==0)mp[a]=i;
        else{if(i<mp[a])mp[a]=i;}
    }ex=nax;
    map<ll,ll>::iterator it;
    for(it=mp.begin();it!=mp.end();it++) if(it->first<ex){ex=it->first;mx=it->second;}
    cout<<mx<<'\n';
}
int main()
{
    //IOS;
    double start_time = clock();
    ll t=1,mex=1;
   //cin>>t;
    while(t--){
        solve();
    }
    double end_time = clock();
    //fprintf(stderr, "Time = %lf\n", (end_time - start_time) / CLOCKS_PER_SEC);
    return 0;
}


Measured memory_bytes: 3736