#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (int i = (int)a; i < (int)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF 1000000000
#define PI 3.14159265359
#define EPS 1e-12

int dp[1010];

int main(void)
{
  int n, v[1010] = {0};
  cin >> n;
  REP(i, n) cin >> v[i];

  if(n == 1) {cout << v[0] << endl; return 0;}
  else if(n == 2) {cout << max(v[0], v[1]) << endl; return 0;}

  dp[0] = v[0]; dp[1] = v[1];
  FOR(i, 2, n) {
    int m = -INF;
    REP(j, i-1) {
      m = max(m, dp[j]);
    }
    dp[i] = max(m + v[i], dp[i-1]);
  }

  cout << dp[n-1] << endl;

  return 0;
}