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//Sylwia Sapkowska 
#include <bits/stdc++.h> 
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;

typedef pair<int, int> T;
const int oo = 1e9+7;

void solve(){
    int n; cin >> n;
    vector d(n+1, vector<int>(n+1, oo));
    for (int i = 1; i<=n; i++) d[i][i] = 0;
    for (int i = 1; i<=n; i++){
        for (int j = 1; j<=n; j++){
            char c; cin >> c;
            if (c == '1') {
                d[i][j] = 1;
            }
        }
    }    
    for (int k = 1; k <= n; ++k) {
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= n; ++j) {
                d[i][j] = min(d[i][j], d[i][k] + d[k][j]); 
            }
        }
    }    
    int ans = oo;
    for (int u = 1; u <= n; u++){
        for (int v = 1; v <= n; v++){
            int curr = 0;
            for (int i = 1; i<=n; i++){
                for (int j = 1; j<=n; j++){
                    curr = max(curr, min({d[i][j], d[i][u] + d[v][j], d[i][v] + d[u][j]}));
                }
            }
            ans = min(ans, curr);
        }
    }
    cout << ans << "\n";
}
 
int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
    cin >> t;
    while (t--) solve();

    return 0;
}