#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define db double
#define fi first
#define se second
#define pii pair<int,int>
#define vi vector<int>

using namespace std;

const int maxn=2e5; 
int n,a[maxn+5]; 
int main() {
	scanf("%d",&n);
	for (int i=1;i<=n;i++) {
		scanf("%d",&a[i]); 
	}
	sort(a+1,a+n+1);
	int ans=0; 
	for (int j=n;j>=n-1;j--) {
		ans+=max(a[j],0); 
	}
	cout<<ans<<'\n'; 
	return 0;
}