#include <iostream>
#include <fstream>
using namespace std;
#define DIM 1000001
int nr_numere,vector[DIM],maxim,op;
int main()
{
    ifstream fin("operatii.in");
    ofstream fout("operatii.out");
    fin>>nr_numere;
    for(int i=0;i<nr_numere;i++)
    {
        fin>>vector[i];
    }
    int anterior=vector[0],consecutive=1;
    for(int i=1;i<nr_numere;i++)
    {
        if(anterior==vector[i] && anterior!=0)
        {
            consecutive++;
            maxim=max(maxim,anterior);
        }
        else
        {
            maxim=max(maxim,anterior);
            if(maxim>0)
            {
                op+=maxim; 
            }
            maxim=-1;
            consecutive=1;
            
        }
        anterior=vector[i];
    }
    if(consecutive>1)
    {
        if(maxim>0)
        {
            op+=maxim; 
        }
    }
    fout<<op<<'\n';
    fout.close();
}