#include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
int t;
cin>>t;
while(t--){
int n;
cin>>n;
// vector<string>v;
vector<vector<char>>v(n,vector<char>(n));
for(int i=0;i<n;i++){
string s;
cin>>s;
sort(s.begin(),s.end());
// v.push
for(int j=0;j<s.size();j++){
v[i][j]=s[j];
}
}
string s1=" ",s2=" ";
int flag=1;
for(int i=0;i<v.size();i++){
for(int j=0;j<v[0].size();j++){
s1+=v[j][i];
}
s2=s1;
//cout<<s2<<"\n";
sort(s1.begin(),s1.end());
//cout<<s1<<"\n";
if(s1!=s2){
flag=0;
break;
}
s1=" ",s2=" ";
}
if(flag==1)
cout<<"YES"<<"\n";
else
cout<<"NO"<<"\n";
}
return 0;
}
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