#include<stdio.h>
#define min(A,B) ((A) < (B) ? (A) : (B))
#define max(A,B) ((A) > (B) ? (A) : (B))

int a[1500][1500];

int main()
{
        int n;
        freopen("INPUT.TXT", "r", stdin);
        freopen("OUTPUT.TXT", "w", stdout);
        scanf("%d\n",&n);
        int i,j,result = 0;
        for(i=1;i<=n;i++)
        {
                for(j=1;j<=n;j++)
                {
                        char k;
                        scanf("%c", &k);
                        if(k == '1')
                        {
                                int m = min(a[i][j-1],a[i-1][j]);
                                m = min(m,a[i-1][j-1]);
                                a[i][j] = m + 1;
                                result = max(result, a[i][j]);
                        }
                }
                scanf("\n");
        }
        printf("%d\n",result*result);
        fclose(stdin);
        fclose(stdout);
        return 0;
}