#include<bits/stdc++.h>
using namespace std;
int main(){
  int n,a[100],cnt=0,sum=0,flag=0;
  cin>>n;
  for(int i=0;i<n;++i) cin>>a[i];
  sort(a,a+n,greater<int>());
  for(int i=0;i<n;++i){
    if(a[i]%2==0) sum+=a[i];
    else ++cnt;
  }
  if(cnt%2) --cnt;
  for(int i=0;i<n&&flag!=cnt;++i){
    if(a[i]%2) {
      sum+=a[i];
      ++flag;
    }
  }
  cout<<sum/2<<endl;
  return 0;
}

