// Source: https://usaco.guide/general/io

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int INF = 1e12;

signed main() {
    int n;cin>>n;
    int a=0,b=0;
    for(int i = 0;i<n;i++){
        if(i==0)cin>>a;
        else if(i==1){
            cin>>b;
            b+=a;
        }
        else{
            int c;cin>>c;
            if(i%2==1){
                b=min(a,b)+c;
            }
            else{
                a=min(a,b)+c;
            }
        }
        //cout<<a<<' '<<b<<endl;
    }
    if(n%2==1){
        cout<<a;
    }
    else{
        cout<<b;
    }

}