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#include <bits/stdc++.h>

using namespace std;

const int Base = 4 * 1e2 + 7;
int Pierdylion = 1e9 + 7;

basic_string<char32_t> graf[Base];
deque<pair<int, int>> q;
// priority_queue<pair<int, int>> q;
int odw[Base];

int t, n;
int X, Y;
int Max, Idx = 1, Min = Pierdylion;
int MX, MY;

int WczytajInta()
{
    char c;
    int wyn = 0;
    while(1) {
        c = getchar();
        if(c == ' ' or c == '\n' or c == EOF) break;
        wyn *= 10;
        wyn += int(c - '0');
    }
    return wyn;
}

void BFS(int x)
{
    odw[x] = 0;
    q.push_back({0, x});
    // q.push({0, x});
    pair<int, int> gura;
    while(!q.empty()) {
        gura = q.front();
        q.pop_front();
        if(gura.first > odw[gura.second]) continue;
        // gura = q.top();
        // q.pop();
        // if(gura.first * -1 > odw[gura.second]) continue;
        if(gura.second == X) {
            if(odw[Y] > odw[gura.second]) {
                odw[Y] = odw[gura.second];
                q.push_front({odw[Y], Y});
                // q.push({-1 * odw[Y], Y});
            }
        } else if(gura.second == Y) {
            if(odw[X] > odw[gura.second]) {
                odw[X] = odw[gura.second];
                q.push_front({odw[X], X});
                // q.push({-1 * odw[X], X});
            }
        }
        for(int i : graf[gura.second]) {
            if(odw[i] > odw[gura.second] + 1) {
                odw[i] = odw[gura.second] + 1;
                q.push_back({odw[i], i});
                // q.push({odw[i] * -1, i});
            }
        }
    }
}

int main()
{
    t = WczytajInta();
    char c;
    bool czy = 0;
    for(int z = 0; z < t; z++) {
        n = WczytajInta();
        Min = Pierdylion;
        for(int i = 1; i <= n; i++) graf[i].clear();
        for(int i = 1; i <= n; i++) {
            for(int j = 1; j <= n; j++) {
                c = getchar();
                if(i == j) continue;
                if(c == '1') {
                    graf[i].push_back(j);
                }
            }
            c = getchar();
        }
        for(int i = 1; i <= n; i++) {
            for(int j = i + 1; j <= n; j++) {
                X = i;
                Y = j;
                Max = 0; Idx = 1;
                for(int k = 1; k <= n; k++) odw[k] = Pierdylion;
                czy = 0;
                BFS(1);
                for(int k = 1; k <= n; k++) {
                    if(Max <= odw[k]) {
                        Max = odw[k];
                        Idx = k;
                    }
                    if(odw[i] == Pierdylion) {
                        czy = 1; break;
                    }
                }
                if(czy) continue;
                for(int k = 1; k <= n; k++) odw[k] = Pierdylion;
                BFS(Idx);
                // cerr << i << " " << j << " " << Idx << "\n";
                Max = 0; Idx = 1;
                for(int k = 1; k <= n; k++) {
                    Max = max(Max, odw[k]);
                }
                if(Max < Min) {
                    Min = Max;
                    MX = X;
                    MY = Y;
                }
                // Min = min(Min, Max);
            }
        }
        printf("%d\n", Min);
        // cerr << (z + 1) << "  :  " << MX << " " << MY << "\n";
    }
}