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

#define FOR( i, m, n )   for( int i = m; i < n; i++ )
#define REP( i, n )      FOR( i, 0, n )
#define ALL( a )         (a).begin(), (a).end()

int main(){
  int n; cin >> n;
  vector<int> a( n ), o ( n );

  int res = 0, mino = 1001, odd = 0;
  REP( i, n ){
    cin >> a[i];
    res += a[i];
    if( a[i] % 2 == 1 ){
      odd++;
      mino = min( mino, a[i] );
    }
    
  }

  
  if( odd % 2 == 1 ) res -= mino;
    

  cout << res / 2 << endl;
}

