#include<iostream>
#include<cstdio>
#include<queue>
#define maxn 1005
using namespace std;
int T,n,a[maxn][maxn],cnt; queue<int> q; bool leaf[maxn],vis[maxn],vvis[maxn]; int fa[maxn];
int findfa(int x){return fa[x]==x?x:fa[x]=findfa(fa[x]);}
void unionn(int p1,int p2){int r1=findfa(p1),r2=findfa(p2); if(r1!=r2) fa[r1]=r2;}
void set(){for(int i=1;i<=n;i++) a[i][0]=2,leaf[i]=vvis[i]=0,fa[i]=i; while(!q.empty()) q.pop(); cnt=0;}
int findnex(int p){
	for(;a[p][0]<=n;a[p][0]++) if(!leaf[a[p][a[p][0]]]&&findfa(p)!=findfa(a[p][a[p][0]])) return a[p][a[p][0]];
	else if(!leaf[a[p][a[p][0]]]) return 0; return 0;
}
void dfs(int p){
	int nxt=findnex(p); if(nxt==0) return; printf("%d %d\n",p,nxt); cnt++; unionn(p,nxt); vis[nxt]=1;
	if(cnt==n-1) return; dfs(nxt);
}
int main(){
	scanf("%d",&T); while(T--){
		scanf("%d",&n); set(); for(int i=1;i<=n;i++){for(int j=1;j<=n;j++) scanf("%d",&a[i][j]); a[i][n+1]=n;}
		for(int i=1;i<=n;i++) if(!vvis[a[i][n]]) q.push(a[i][n]),vvis[a[i][n]]=1;
		while(cnt!=n-1){
			int top=q.front(); q.pop(); leaf[top]=vis[top]=1; dfs(top); if(cnt==n-1) break;
			for(int i=1;i<=n;i++){
				while(leaf[a[i][a[i][n+1]]]) a[i][n+1]--; a[i][n+1]++;
				if(leaf[a[i][a[i][n+1]]]&&!vvis[a[i][a[i][n+1]-1]])
					q.push(a[i][a[i][n+1]-1]),vvis[a[i][a[i][n+1]-1]]=1,a[i][n+1]--;
			}	
			if(q.empty()&&cnt!=n-1) for(int i=1;i<=n;i++) if(vis[i]&&!vvis[i]) q.push(i),vvis[i]=1;
		}
	}
	return 0;
}