#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize(2)
typedef long long LL;
char arr[255][255];
int n;
#define yes (void)(puts("YES"));
#define no (void)(puts("NO"));
void solve(){
    bool ok;
    scanf("%d",&n);
    for (int i=1;i<=n;++i){
        scanf("%s",arr[i]+1);
    }
    for (int i=1;i<=n;++i){
        ok=0;
        for (int j=2;j<n;++j){
            if (arr[i][j]==arr[i][j-1]&&arr[i][j]==arr[i][j+1]){ok=1;break;}
        }
        if (ok){return yes;}
    }
    for (int i=1;i<=n;++i){
        ok=0;
        for (int j=2;j<n;++j){
            if (arr[j][i]==arr[j-1][i]&&arr[j][i]==arr[j+1][i]){ok=1;break;}
        }
        if (ok){return yes;}
    }
    return no;
}
int main(){
    int T;scanf("%d",&T);++T;while (--T){solve();}
    return 0;
}