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#include<stdio.h>
using namespace std;
char a[510][510];
int n;
int main(){
    scanf("%d",&n);
    for(int i=0;i<n;i++){
            scanf("%s",a[i]);
    }int ans=0;
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            int k = 0;
            while(k<=i&&k+i<n&&k<=j&&k+j<n&&a[i-k][j]=='1'&&a[i+k][j]=='1'&&a[i][j-k]=='1'&&a[i][j+k]=='1')k++;
            if(k>ans)ans=k;
        }
    }
    if(ans==0)ans=1;
    printf("%d\n",ans-1);
    return 0;
}
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