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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=(a);i<(n);i++)
#define per(i,a,n) for (int i=(n)-1;i>=(a);i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(1234); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=410;
int n,g[N][N];
char s[N];
bitset<N> bs[N][N];
VI vec[N];
void solve() {
	scanf("%d",&n);
	rep(i,0,n) rep(j,0,n) g[i][j]=(i==j)?0:n+1;
	rep(i,0,n) {
		scanf("%s",s);
		rep(j,0,n) if (s[j]=='1') g[i][j]=1;
	}
	rep(k,0,n) rep(i,0,n) rep(j,0,n) g[i][j]=min(g[i][j],g[i][k]+g[k][j]);
	int ans=0;
	rep(i,0,n) rep(j,i+1,n) ans=max(ans,g[i][j]);
	rep(i,0,n) {
		bs[i][n].reset();
		rep(d,0,n) vec[d].clear();
		rep(j,0,n) vec[g[i][j]].pb(j);
		per(d,0,n) {
			bs[i][d]=bs[i][d+1];
			for (auto x:vec[d]) bs[i][d][x]=1;
		}
	}
	rep(i,0,n) rep(j,i+1,n) {
		auto check=[&](int w) {
			if (w<=0) return false;
			rep(x,0,n) {
				if ((bs[x][w+1]&bs[j][max(w+1-g[x][i],0)]&bs[i][max(w+1-g[x][j],0)]).any()) return false;
			}
			return true;
		};
		while (check(ans-1)) --ans;
	}
	printf("%d\n",ans);
}

int _;
int main() {
	for (scanf("%d",&_);_;_--) {
		solve();
	}
}