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#include <iostream>
#include <climits>
using namespace std;

#define INF INT_MAX
#define maxm maxn *maxn
#define maxn 401

long long odl[401][401];
long long odl2[401][401];
int odl_sum[401];
void wypisz(long long V)
{   int ile=0;
    for (long long i = 0; i < V; i++)
    {   ile=0;
        for (long long j = 0; j < V; j++)
        {
            if (odl[i][j] != INF)
            {
                cout << "* ";
            }
            else if (odl[i][j] <= -INF + maxm * 100)
                cout << "-oo ";
            else
            {
                cout << odl[i][j] << ' ';
                ile+=odl[i][j] ;
            }
        }
        cout << ile<<" \n";
    }
}
void wypisz_mod(long long V)
{   int max=0, maxi=0, maxi2=0, max_elem=0, max_elemp=0, max_elemi;;
    for (long long i = 0; i < V; i++)
    {   odl_sum[i]=0;
        max_elemp=0;
        for (long long j = 0; j < V; j++)
        {
            if (!(odl[i][j] == INF && (odl[i][j] <= -INF + maxm * 100) ))
            {
               // cout << odl[i][j] << ' ';
                odl_sum[i]+=odl[i][j] ;
                if(max_elemp<odl[i][j]){
                    max_elemp=odl[i][j];
                    max_elemi = j;
                }
        }
        
       // cout << ile<<" \n";
    }
    if(max<odl_sum[i]){
        max=odl_sum[i];
        maxi=i;
        maxi2=max_elemi;
        //max elem
    }
}
odl2[maxi][maxi2]=0;
odl2[maxi2][maxi]=0;

}
void czysc(int n){
    for (long long i = 0; i < n; i++)
        {
            for (long long j = 0; j < n; j++)
            {
                odl[i][j] = INF;
                odl2[i][j]=INF;
            }
           
        }
}
void floydWarshall(long long V, long long odl[401][401])
{   
    
    long long i, j, k;

    for (k = 0; k < V; k++)
    {

        for (i = 0; i < V; i++)
        {

            for (j = 0; j < V; j++)
            {

                if (
                    odl[i][k] < INF &&
                    odl[k][j] < INF &&
                    odl[i][k] + odl[k][j] <= odl[i][j]
                    )
                {
                        odl[i][j] = odl[i][k] + odl[k][j];
                        if (odl[k][k] < 0)
                            odl[i][j] = -INF;
                }
            }
        }
    }
    wypisz_mod(V);
}

int main()
{

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long t,n;

    cin >> t;
    for(int i=0;i<t;i++){
        
        cin>>n;
       
        
        char a;
        czysc(n);

            for (long long k = 0; k < n; k++)
            {   
                for(long long i=0;i<n;i++){
                    cin>>a;
                    if(a=='1'){
                        odl[k][i]=1;
                        odl2[k][i]=1;
                    }
                    
                    
                }
               
            }
            
            
     for(int i=0;i<n;i++){
             odl[i][i] = 0;
             odl2[i][i]=0;
        }
        // Function call
        floydWarshall(n, odl);
        floydWarshall(n,odl2);
        long long maxx=0;
        for (long long k = 0; k < n; k++)
            {   
                for(long long i=0;i<n;i++){
                    
                        maxx=max(odl2[k][i],maxx);
                    
                    
                    
                }
               
            }
            cout<<maxx<<endl;
    }
    
    return 0;
}