#include <bits/stdc++.h>
using namespace std;
#define MM ios_base::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
int main(){
MM
int n,m,sum=0;
cin>>n>>m;
vector<int> v(n);
for (auto &i:v) {
cin>>i;
}
sort(v.begin(),v.end());
for (int i=-m;i<=m;i++) {
if (v[sum]!=i) {
cout<<i;
break;
}
if (sum==n-1) {
cout<<v[sum]+1;
break;
}
sum++;
}
}
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