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#include <bits/stdc++.h>
using namespace std;
#define vec_2d vector< vector< int > >
typedef long long ll;
const int INF = 1'000;
int T;
vector< int > answer;
int x, y;

int FW(int N, vec_2d dp){
    for(int k = 0; k < N; k++){
        for(int i = 0; i < N; i++){
            for(int j = 0; j < N; j++){
                if(dp[i][j] > dp[i][k]+dp[k][j]){
                    dp[i][j] = dp[i][k]+dp[k][j];
                }
            }
        }
    }
    int Max = 0;
    for(int i = 0; i < N; i++){
        for(int j = 0; j < N; j++){
            if(dp[i][j] >= Max){
                Max = dp[i][j];
                x = i, y = j;
            }
        }
    }
    return Max;
}

void solve(){
    int N;
    cin >> N;
    vec_2d vec(N);
    vec_2d dp(N, vector<int>(N));
    for(int i = 0; i < N; i++){
        string s;
        cin >> s;
        for(int j = 0; j < N; j++){
            dp[i][j] = INF;
            int a = s[j]-'0';
            if(a == 1){
                vec[i].push_back(j);
                vec[j].push_back(i);
                dp[i][j] = 1, dp[j][i] = 1;
            }
        }
        dp[i][i] = 0;
    }
    int Max = FW(N, dp);
    for(int i = 0; i < N; i++){
        for(int j = 0; j < N; j++){ dp[i][j] = INF; }
        for(auto j : vec[i]){
            dp[i][j] = 1;
        }
        dp[i][i] = 0;
    }
    dp[y][x] = 0;
    dp[x][y] = 0;
    Max = FW(N, dp);
    answer.push_back(Max);
    return;
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

    int T;
    cin >> T;
    for(int t = 0; t < T; t++){
        solve();
    }
    for(int t = 0; t < T; t++){
        cout << answer[t] << "\n";
    }
    return 0;
}