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#include <iostream>
using namespace std;
const int mxm=505;
int n;
char a[mxm][mxm];
int f[mxm];
int main() {
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i]+1;
    }
    int ans=0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(a[i][j]=='1'){
            //cout<<a[i][j]<<" ";
            int k=1,k1=1;
            while(j-k>=1&&j+k<=n&&a[i][j-k]==a[i][j+k]&&a[i][j-k]=='1')k++;
            while(i-k1>=1&&i+k1<=n&&a[i-k1][j]==a[i+k1][j]&&a[i-k1][j]=='1')k1++;
            ans=max(ans,min(k,k1));
            }
        }
        //cout<<endl;
    }
    cout  << ans-1<<endl;
    return 0;
}
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