#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;


int V[1005];
int dp[1005];

int main(){
  int N;

  cin >> N;
  rep(i,N){
    cin >> V[i];
    dp[i] = V[i];
  }

  rep(i,N){
    rep(j,i-1){
      dp[i] = max(dp[i], dp[j]+V[i]);
    }
  }

  int ret = 0;
  rep(i,N){
    ret = max(ret, dp[i]);
  }
  
  
  cout << ret << endl;
  
  return 0;
}