#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001


int main(){
	
	int n;
	cin>>n;
	vector<int> a(n);
	vector<int> c(1000000,0);
	rep(i,n){
		cin>>a[i];
		c[a[i]]++;
	}
	int ok = -1,ng = 100005;
	while(ng-ok>1){
		int mid = (ok+ng)/2;
		int r = 0 ;
		int NG = 0;
		rep(i,c.size()){
			if(i<=mid){
				if(c[i]==0)NG = 1900;
				else if(c[i]==1)NG++;
				else r += c[i]-2;
			}
			else{
				r += c[i];
			}
		}
		if(NG==0 || (NG==1&&r>0))ok = mid;
		else ng = mid;
	}
	cout<<ok+1<<endl;
	
	
	return 0;
}