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#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
#define vec vector
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

void cvb(vector <bool> v){
    for (bool x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvs(vector <string>  v){
    for (auto a: v){
        cout<<a<<"\n";
    }
}

void cvp(vector <pii> a){
    for (auto p: a){
        cout<<p.first<<' '<<p.second<<"\n";
    }
    cout<<"\n";
}

#include <fstream>

string bin(int x){
    string r="";
    while (x > 0){
        r += (x%2) + '0';
        x/=2;
    }
    reverse(r.begin(), r.end());
    return r;
}

int ans=-1,n;

void f(vector <int> a){
    vector <int> r(2);
    int pf=0;
    for (int i = 0; i < n; ++i){
        pf += a[i];
        r[a[i]%2]++;
    }
    if (r[0] != r[1] && r[pf%2] == max(r[0], r[1])){
        ans = max(ans, pf);
    }
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    string t;
    ifstream fl("271.txt");
    getline (fl, t);
    n = stoi(t);
    cout<<n<<"\n";
    vector <pii> v;
    while (getline(fl, t)){
        int a,b;
        int i = find(t.begin(), t.end(), ' ') - t.begin();
        a = stoi(t.substr(0, i));
        b = stoi(t.substr(i+1, t.size() - i));
        //cout<<a<<' '<<b<<' '<<(a+b)<<"\n";
        v.push_back({a,b});
    }
    int k;
    for (int i = 0; i < pow(2, n); ++i){
        t=bin(i);
        vector <int> a(n);
        for (int j = 0; j < n; ++j){
            if (t[j] == '0'){
                a[j] = v[j].first;
            }
            else{
                a[j] = v[j].second;
            }
        }
        f(a);
    }
    cout<<ans;
}