#include <bits/stdc++.h>
using namespace std;
#define FOR(i,n) for (int i=1;i<=n;i++)
#define REP(i,a,b) for (int i=a;i<=b;i++)
#define pb push_back
#define mp make_pair
#define ll long long
#define pos(x,y) (x+(y)*n)
const int N=100000+10;
const int inf=0x3f3f3f3f;
const ll mod=1000000007;
const double eps=1e-8;

int n;
string s;
int a[101][201];
int f[101][201][201];
int ans;
int main() {
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    scanf("%d\n",&n);
    FOR(i,n) {
        getline(cin,s);
        int cnt=0;
        for (int j=0;j<s.size();j++) {
            if (s[j]=='-') a[i][++cnt]=0;
            else if (s[j]=='#') a[i][++cnt]=1;
        }
    }
    FOR(i,n) {
        FOR(j,2*(n+1-i)-1) {
            if (j%2==1&&a[i][j]==0) {
                f[i][j][1]=1;
                ans=max(ans,1);
            }
        }
    }
    FOR(i,n) {
        int len=2*(n+1-i)-1;
        FOR(j,len) {
            if (j%2==1&&a[i][j]==0) {
                if (i>1&&a[i-1][j]==0&&j+2<=len+2&&a[i-1][j+1]==0&&a[i-1][j+2]==0) for (int k=n;k>=2;k--) {
                    if (f[i-1][j][k-1]&&f[i-1][j+2][k-1]) {
                        f[i][j][k]=1;
                        ans=max(ans,k);
                        break;
                    }
                }
            }
        }
    }
    cout<<ans*ans<<endl;
    return 0;
    memset(f,0,sizeof f);
    FOR(i,n) {
        FOR(j,2*(n+1-i)-1) {
            if (j%2==0&&a[i][j]==0) {
                f[i][j][1]=1;
                ans=max(ans,1);
            }
        }
    }
    for (int i=n;i>=1;i--) {
        int len=2*(n+1-i)-1;
        FOR(j,len) {
            if (j%2==0&&a[i][j]==0) {
                if (i<n&&a[i+1][j]==0&&j-2>=1&&a[i+1][j-1]==0&&a[i+1][j-2]==0) for (int k=n;k>=2;k--) {
                    if (f[i+1][j-2][k-1]&&f[i+1][j][k-1]) {
                        f[i][j][k]=1;
                        ans=max(ans,k);
                        break;
                    }
                }
            }
        }
    }
    cout<<ans*ans<<endl;
    return 0;
}