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//~ mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//~ while (clock()<=69*CLOCKS_PER_SEC)
//~ #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
//~ #pragma GCC target ("avx2")
//~ #pragma GCC optimize("Ofast")
//~ #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//~ #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define shandom_ruffle random_shuffle

using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vll=vector<ll>;
const int nax=407;

int n;

char wcz[nax];
int mac[nax][nax];

int naj[nax][nax];

int wyn;

int check(int a, int b, int cel)
{
	for (int i=1; i<=n; i++)
	{
		if (mac[a][i]<=mac[b][i])
		{
			if (mac[a][i]+naj[i][b]>cel)
				return 0;
		}
		else
		{
			if (mac[b][i]+naj[i][a]>cel)
				return 0;
		}
	}
	return 1;
}

void test()
{
	scanf("%d", &n);
	wyn=n;
	for (int i=1; i<=n; i++)
		for (int j=1; j<=n; j++)
			naj[i][j]=0;
	for (int i=1; i<=n; i++)
		for (int j=1; j<=n; j++)
			mac[i][j]=n;
	for (int i=1; i<=n; i++)
		mac[i][i]=0;
	for (int i=1; i<=n; i++)
	{
		scanf("%s", wcz+1);
		for (int j=1; j<=n; j++)
			if (wcz[j]=='1')
				mac[i][j]=1;
	}
	for (int l=1; l<=n; l++)
		for (int i=1; i<=n; i++)
			for (int j=1; j<=n; j++)
				mac[i][j]=min(mac[i][j], mac[i][l]+mac[l][j]);
	for (int i=1; i<=n; i++)
	{
		for (int j=i+1; j<=n; j++)
		{
			while(check(i, j, wyn-1))
			{
				wyn--;
				for (int a=1; a<=n; a++)
					for (int b=1; b<=n; b++)
						if (mac[a][b]==wyn)
							for (int c=1; c<=n; c++)
								naj[a][c]=max(naj[a][c], mac[b][c]);
			}
		}
	}
	
	
	printf("%d\n", wyn);
}

int main()
{
	int t;
	scanf("%d", &t);
	while(t--)
		test();
	return 0;
}