func_code_string: /*    * yaswanth phani kommineni    */   #include <bits/stdc++.h>   using namespace std;   typedef long long int ll;   #define endl   n ;         void solve(){    ll n;    cin >> n;    n*=2;    vector <ll> v(n);    map <ll,ll> m;    for(ll i=0;i<n;i++){     cin >> v[i];     m[v[i]]++;    }    sort(v.begin(),v.end());    for(ll i=0;i<n-1;i++){     auto mp = m;     auto V = v;     vector <pair<ll,ll>> ans;     ans.push_back(make_pair(v[n-1],v[i]));     mp[v[n-1]]--;     mp[v[i]]--;     ll cur = v[n-1];     while(true){      while(!V.empty() && !mp[V.back()]){       V.pop_back();      }      if(V.empty()) break;      ll last = V.back();      mp[last]--;      if(!mp[cur-last]){       break;      }      ans.push_back(make_pair(last,cur-last));      mp[cur-last]--;      cur = last;     }     if((ll)ans.size()==n/2){      cout <<  YES  << endl;      cout << ans.front().first + ans.front().second << endl;      for(auto x : ans){       cout << x.second <<     << x.first << endl;      }      return;     }    }    cout <<  NO  << endl;   }      int main(){    //freopen( input.txt , r ,stdin);    //freopen( output.txt , w ,stdout);    ios_base::sync_with_stdio(false);    cin.tie(0);    cout.tie(0);    int tc;    tc = 1;    cin >> tc;    for(int i=1;i<=tc;i++){     solve();    }    return 0;   }   