#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define REP(i,n) FOR(i,0,n)
#define pb push_back
#define en "\n"
#define ITER(i,a) for( typeof(a.begin()) i=a.begin();i!=a.end();i++)
#define mod 1000000007
#define mpp make_pair
#define mes(a,b) memset((a),(b),sizeof((a))
typedef map<int,int> MI;
typedef pair<int,int>   PI;
typedef vector<int> VI;
typedef long long int LL;

int main() {
	// your code goes here
	ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin>>n;
    n=(2*n);
    int a[n];
    for(int i=0;i<n;i++)
    cin>>a[i];
    sort(a,a+n);
    int ans=0;
    for(int i=0;i<n;i+=2)
    {
        ans=ans+a[i];
    }
    cout<<ans;
	return 0;
}

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(v) v.begin(),v.end()
#define len(x) (ll)(x).length()
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
const int INF=1e9;
const ll INFS=1e18;
const int MOD=INF+7;
const int di[] = {-1,0,1,0};
const int dj[] = {0,-1,0,1};
 
int main() {
  int n;
  cin>>n;
  map<int,int> mp;
  rep(i,n){
    int a;
    cin>>a;
    if(mp[a]!=1){
      mp[a]=1;
    }else{
      mp[a]=0;
    }
  }
  int ans=0;
  for(auto x:mp){
    if(x.second==1){
      ans++;
    }
  }
  cout<<ans<<endl;
}