1 #include <set>
 2 #include <map>
 3 #include <queue>
 4 #include <deque>
 5 #include <stack>
 6 #include <cmath>
 7 #include <cstdio>
 8 #include <vector>
 9 #include <string>
10 #include <cstring>
11 #include <fstream>
12 #include <iostream>
13 #include <algorithm>
14 using namespace std;
15 
16 #define eps 1e-8
17 #define pb push_back
18 #define PI acos(-1.0)
19 #define INF 0x3f3f3f3f
20 #define clr(a,b) memset(a,b,sizeof(a)
21 #define FAST_IO ios::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
22 
23 const int N=600;
24 typedef long long ll;
25 typedef unsigned long long ull;
26 char s[N][N];
27 
28 int main(){
29     int n,ans=0;
30     scanf("%d",&n);
31     for(int i=1;i<=n;i++){
32         scanf("%s",s[i]+1);
33     }
34     for(int i=2;i<n;i++){
35         for(int j=2;j<n;j++){
36             if(s[i][j]=='1'){
37                 int l=0,r=0,u=0,d=0;
38                 for(int k=j+1;k<=n;k++) if(s[i][k]=='1') r++;else break;
39                 for(int k=j-1;k>=1;k--) if(s[i][k]=='1') l++;else break;
40                 for(int k=i+1;k<=n;k++) if(s[k][j]=='1') d++;else break;
41                 for(int k=i-1;k>=1;k--) if(s[k][j]=='1') u++;else break;
42                 l=min(l,r);
43                 u=min(u,d);
44                 ans=max(ans,min(l,u));
45             }
46         }
47     }
48     printf("%d\n",ans);
49     return 0;
50 }