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#include<bits/stdc++.h>
using namespace std;

map<pair<int, int>, int> mapa;

pair<int, int> bfs(int w, int n, vector<int> graf[]){
    vector<int> odl(n + 1, INT_MAX);
    deque<int> q;
    odl[w] = 0;
    q.push_back(w);
    while(!q.empty()){
        w = q.front();
        q.pop_front();
        for(auto u : graf[w]){
            int waga;
            if(mapa[{u, w}] == 1) waga = 1;
            else waga = 0;
            if(odl[w] + waga < odl[u]){
                odl[u] = odl[w] + waga;
                if(waga == 0) q.push_front(u);
                else q.push_back(u);
            }
        }
    }
    
    int node = w;
    int maks_odl = 0;
    for(int i = 1; i <= n; i++){
        if(odl[i] > maks_odl){
            maks_odl = odl[i];
            node = i;
        }
    }
    return {maks_odl, node};
}

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

    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        int wynik = INT_MAX;
        mapa.clear();
        vector<int> graf[n + 1];
        for(int i = 1; i <= n; i++){
            string s;
            cin >> s;
            for(int j = 1; j <= n; j++){
                if(s[j - 1] == '1'){
                    graf[i].push_back(j);
                    mapa[{i, j}] = 1;
                }
            }
        }
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= n; j++){
                if(i == j) continue;
                if(mapa[{i, j}] == 0){
                    graf[i].push_back(j);
                    graf[j].push_back(i);
                }
                pair<int, int> pocz = bfs(1, n, graf);
                wynik = min(wynik, bfs(pocz.second, n, graf).first);
                if(mapa[{i, j}] == 0){
                    graf[i].pop_back();
                    graf[j].pop_back();
                }
            }
        }
        cout << wynik << '\n';
    }
}