#include<cstdio>
#include<cstring>
using namespace std;
int n,m,x,y,l,sum,ras,sus[504][504],jos[504][504],dr[504][504];
char a[504][504];
int main()
{
   // freopen("input","r",stdin);
    //freopen("output","w",stdout);
    scanf("%d %d\n",&n,&m);
    for(int i=1;i<=n;i++)
    {
        gets(a[i]+1);
        for(int j=1;j<=m;j++)
            if(a[i][j]=='1')sus[i][j]=sus[i-1][j]+1;
            else sus[i][j]=0;
    }
    for(int i=n;i>=1;i--)
        for(int j=m;j>=1;j--)
        {
            if(a[i][j]=='1')
            {
                jos[i][j]=jos[i+1][j]+1;
                dr[i][j]=dr[i][j+1]+1;
            }
            else jos[i][j]=dr[i][j]=0;
        }
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            if(a[i][j]=='1')
            {
                sum=0;
                x=i;
                y=j;
                l=jos[x][y];
                if(l>1)sum+=l;
                else continue;
                x+=l-1;
                l=dr[x][y];
                if(l>1)sum+=l;
                else continue;
                y+=l-1;
                l=sus[x][y];
                if(l>1)sum+=l;
                else continue;
                sum-=2;
                if(sum>ras)ras=sum;;
            }
    printf("%d",ras);
    return 0;
}