#include<bits/stdc++.h>
#define fo(s) freopen(s".in","r",stdin),freopen(s".out","w",stdout)
#define Ts template<typename Ty,typename... Ar>
#define Tp template<typename Ty>
#define ll long long
#define RS register
#define gc getchar
#define pc putchar
#define I inline
using namespace std;
Tp I Ty wmax(Ty a,Ty b){return a>=b? a:b;}
Tp I Ty wmin(Ty a,Ty b){return a<=b? a:b;}
namespace WrongIO
{
	Tp I void read(Ty &x){x=0;Ty opt=1;char c=gc();while(!isdigit(c)&&c!='-')c=gc();if(c=='-')opt=-1,c=gc();while(isdigit(c))x=(x<<3)+(x<<1),x+=c-'0',c=gc();x*=opt;return;}
	Tp I void write(Ty x){short OI_USE[50],OI_top=0;if(x<=0) if(x==0)pc('0');else pc('-'),x*=-1;while(x)OI_USE[++OI_top]=x%10,x/=10;while(OI_top--)pc(OI_USE[OI_top+1]+'0');return;}
    I void writec(char c[]){int len=strlen(c);for(int i=0;i<len;i++)pc(c[i]);}
    I void writes(string s){int len=s.length();for(int i=0;i<len;i++)pc(s[i]);}
    I void readc(char &c,int l,int r){c=gc(); while(c!=EOF&&(c<l||c>r)) c=gc();}
    I void readc(char &c,char val){c=gc();while(c!=EOF&&c!=val) c=gc();}
    I void readc(char val){char c;c=gc();while(c!=EOF&&c!=val) c=gc();}
    I void readls(string &s){char c=gc();while(c!='\n') s.push_back(c),c=gc();}
    Ts I void read(Ty &x,Ar &...y) {read(x),read(y...);}
} using namespace WrongIO;
int T;
int e[1050][1050],n;
int bcj[1050],ans;
int vis[1050];
int root(int x)
{
	return x==bcj[x]? x:bcj[x]=root(bcj[x]);
}
int main(){
	read(T);
	while(T--)
	{
		pc('\n');
		read(n); for(int i=1;i<=n;i++) bcj[i]=i; 
		memset(vis,0,sizeof(vis)); ans=0;
		for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
		read(e[i][j]);
		for(int i=1;i<=n;i++)
		{
			if(root(e[i][1])!=root(e[i][2]))
			{
				bcj[root(e[i][1])]=root(e[i][2]); ans++;
				write(e[i][1]),pc(' '),write(e[i][2]),pc('\n');
			}
		}
		if(ans==n-1) continue;
		for(int o=n;o>=1;o--)
		{
			
			for(int i=1;i<=n;i++)
			{
				int u=e[i][o],v=e[u][2],id=0;
				if(vis[u]) continue;
				for(int j=1;j<=n;j++)
				{
					if(e[v][j]==u)
					{
						id=j;
						break;
					}
				}int j=2;
				for(;j<=n;j++)
				{
					if(root(e[v][1])!=root(e[v][j])) break;
				}
				
				
				if(id<=n&&j!=n+1)
				{
					if(root(e[v][1])!=root(e[v][j]))
					{
						bcj[root(e[v][1])]=root(e[v][j]); ans++;
						write(e[v][1]),pc(' '),write(e[v][j]),pc('\n');
						break;
					}
				}
			}
			if(ans==n-1) break;
		}
		
		
	}
}