#include<bits/stdc++.h>
using namespace std;
template<typename T>inline void read(T &x){
	x=0;
	bool flag=0;
	char ch=getchar();
	while(ch<'0'||ch>'9') flag=flag||(ch=='-'),ch=getchar();
	while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
	x=flag?-x:x;
}
template<typename T,typename ...Args>inline void read(T &x,Args &...args){
	read(x),read(args...);
}
template<typename T>inline void prt(T x){
	if(x>9) prt(x/10);
	putchar(x%10+'0');
}
template<typename T>inline void put(T x){
	if(x<0) putchar('-'),x=-x;
	prt(x);
}
template<typename T>inline void put(char ch,T x){
	put(x),putchar(ch);
}
template<typename T,typename ...Args>inline void put(char ch,T x,Args ...args){
	put(ch,x),put(ch,args...);
}
#define N 1000005
#define ull unsigned long long
#define ll long long
mt19937_64 rng(time(0));
ull s,a,b,c;
inline ull rd(){
	s^=(s>>11);
	s^=(s<<17);
	s^=(s^a)<<17;
	s^=(s*b)<<17;
	s^=c;
	return s;
}
int T,n;
ll w[N];
vector<ll> val[2],dis[2],pre[2];
inline bool solve(ll ps){
	s=ps,dis[0]=val[0],dis[1]=val[1];
	shuffle(dis[0].begin(),dis[0].end(),rng);
	shuffle(dis[1].begin(),dis[1].end(),rng);
	pre[0]=dis[0],pre[1]=dis[1];
	while(dis[0].size()>1||dis[1].size()>1){
		int c=rd()&1;
		if(dis[c].size()<=1) c^=1;
		ll x=dis[c].back();dis[c].pop_back();
		ll y=dis[c].back();dis[c].pop_back();
		ll z=(x+y)>>1;dis[z&1].emplace_back(z);
	}
	if(dis[0].size()&&dis[1].size()) return 0;
	s=ps,dis[0]=pre[0],dis[1]=pre[1];
	vector<pair<ll,ll>> vec;
	while(dis[0].size()>1||dis[1].size()>1){
		int c=rd()&1;
		if(dis[c].size()<=1) c^=1;
		ll x=dis[c].back();dis[c].pop_back();
		ll y=dis[c].back();dis[c].pop_back();
		vec.emplace_back(x,y);
		ll z=(x+y)>>1;dis[z&1].emplace_back(z);
	}
	for(auto tmp:vec) put(' ',tmp.first),put('\n',tmp.second);
	return 1;
}
inline void solve(){
	read(n),val[0].clear(),val[1].clear();
	for(int i=1;i<=n;i++)
		read(w[i]),val[w[i]&1].emplace_back(w[i]);
	for(int i=1;i<=400;i++)
		if(solve(rng())) return;
	puts("-1");
}
int main(){
	a=rng(),b=rng(),c=rng();
	read(T);
	while(T--) solve();
	return 0;
}