#include <iostream>
#include <math.h>
#include <algorithm>
bool mf (int i,int j) { return (i<j);}
bool mf2 (int i,int j) { return (i>j);}
bool jei(int n, std::vector<int> koliket) {
while (n > 0 && koliket.size() > 0) {
for (int i = 0; i < koliket.size(); i++) {
if (koliket.at(0) > n) {
n -= koliket.at(0);
koliket.erase(koliket.begin());
break;
} else if (koliket.at(i) > n) {
n -= koliket.at(i - 1);
koliket.erase(koliket.begin() + i - 1);
break;
} else if (i == koliket.size() - 1) {
n -= koliket.at(koliket.size() - 1);
koliket.erase(koliket.begin() + koliket.size() - 1);
}
}
//std::cout << koliket.size() << std::endl;
}
if (n == 0) {
//std::cout << og << " voidaan muodostaa" << std::endl;
return true;
} else {
//std::cout << og << " ei voida muodostaa" << std::endl;
return false;
// std::cout << n << std::endl;
}
}
int main() {
int n;
std::vector<int> v;
std::vector<int> s;
std::vector<int> s2;
std::vector<int> sr;
std::cin >> n;
if (n == -1) {
v = {2,2,5,8};
n = 4;
} else if (n == -2) {
v = {1,1,1,2,2,3,5,8,6,7,20};
n = 11;
} else {
for (int i = 0; i < n; i++) {
int t;
std::cin >> t;
v.push_back(t);
}
}
std::sort(std::begin(v), std::end(v));
s.push_back(v.at(0));
sr.push_back(v.at(n-1));
s2.push_back(v.at(n - 1));
for (int i = 0; i < n; i++) {
// std::cout << v.at(i) << " ";
// if (v.at(i) < 10) {
// std::cout << " ";
// }
if (i != 0) {
s.push_back(s.at(i - 1) + v.at(i));
}
if (i != 0) {
sr.push_back(sr.at(i - 1) + v.at(n - i - 1));
}
}
for (int i = 0; i < n; i++) {
s2.push_back(v.at(n - 1) - v.at(i));
}
std::reverse(sr.begin(), sr.end());
/* std::cout << std::endl;
for (int i = 0; i < n; i++) {
std::cout << sr.at(i) << " ";
}
std::cout << std::endl;
/*for (int i = 0; i < n; i++) {
std::cout << s.at(i) << " ";
if (s.at(i) < 10) {
std::cout << " ";
}
}*/
for (int i = 1; i < 10e6 + 1; i++) {
if(std::binary_search (v.begin(), v.end(), i, mf) ||
std::binary_search (sr.begin(), sr.end(), i, mf2) ||
std::binary_search (s2.begin(), sr.end(), i, mf) {
continue;
}
/*if (jei(i, v)) {
continue;
}*/
std::cout << i << std::endl;
break;
}
//int cmax = s.at(n - 1);
//std::cout << std::endl;
return 0;
}
/*
Syöte:
4
2 1 2 7
Tuloste:
6
*/