#include <iostream>

using namespace std;

int v[1001];

int suma(int st, int dr){
int s1,s2,mij;
if(st==dr){if(v[st]%2==0) return v[st];
else return 0;}

else{mij=(st+dr)/2;
     s1=suma(st,mij);
     s2=suma(mij+1,dr);
    return s1+s2;
    }

}

int main()
{
int n,i;
cin>>n;
for(i=1; i<=n; i++)
    cin>>v[i];
cout<<suma(1,n);


}