#include <bits/stdc++.h>
#define SmileHappy  int main()
#define ll long long
#define str string
#define fir first
#define sec second
#define ld long double
#define pb push_back
#define MOD 100000009
#define freopen(name) if(fopen(name".INP","r")) {freopen (name".INP","r",stdin); freopen (name".OUT","w",stdout);}
#define ALL(x) (x).begin(),(x).end()
using namespace std;
bool snt(int num)
{
    if (num < 2) return false;
    for (int i = 2; i * i <= num; ++i)
    {
        if (num % i == 0) return false;
    }
    return true;
}
SmileHappy
{
    freopen("BAI2");
    int n;
    cin >> n;
    vector<int> nums(n);
    for (int i = 0; i < n; ++i)
        cin >> nums[i];
    sort(nums.begin(), nums.end());
    int siuu = 2;
    for (int i = 0; i < n; ++i)
    {
        if (nums[i] > siuu) break;
        else if (nums[i] == siuu) ++siuu;
    }
    while (!snt(siuu)) ++siuu;
    cout << siuu << endl;
    return 0;
}

//yessir deep dak fantasy

`\color{red}{\text{@hoangduy67}}`

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

const int N = 1e7 + 5;

int n, a[N], f[N];

int main() {
    freopen("BAI2.INP", "r", stdin);
   /freopen("BAI2.OUT", "w", stdout);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        f[a[i]] = 1;
    }
    for (int i = 1; i <= N; ++i) {
        if (!f[i] && i > 1) {
            cout << i;
            break;
        }
    }
    return 0;
}