#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
using namespace std;


#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;

/* ここからが本編 */
int main(void)
{
   int i,j,k;
   int n;
   int v[1000];
   int a,b; 
   cin >> n;
   rep(i,n) cin >> v[i];
   if(n == 1) b = v[0];
   else {
      a = v[0];
      b = v[1];
      if(v[0] > v[1]) b = v[0];
      for(i=2;i<n;i++) {
         if(b > a+v[i]) v[i] = b;
         else v[i] =a+v[i];
         a = b; b = v[i];
      }
   }
   cout << b << endl;
   return 0;
}