#include <stdio.h>
#define maxl 210

int i,j,k,n,m,min,op,max,x;
int a[maxl][maxl],b[maxl][maxl],d[maxl][maxl];
int c[maxl][maxl][maxl];
int l[maxl],r[maxl],up[maxl],down[maxl];
char s[maxl];

void calc_v()
{
     for (j=1; j<=m; j++)
     {
         if (op==1) max=l[j-1];
         else max=r[j-1];
         
         for (i=1; i<=n; i++)
             for (k=1; k<=n, i-k+1>0, a[i-k+1][j]==0; k++)
                 if (c[i][j][k]*k>max) max=c[i][j][k]*k;
         
         if (op==1) l[j]=max;
         else r[j]=max;
     }
}

void calc_o()
{
     for (i=1; i<=n; i++)
     {
         if (op==1) max=up[i-1];
         else max=down[i-1];
         
         for (j=1; j<=m; j++)
             for (k=1; k<=n, i-k+1>0 , a[i-k+1][j]==0; k++)
                if (c[i][j][k]*k>max) max=c[i][j][k]*k;
         
         if (op==1) up[i]=max;
         else down[i]=max;
     }
}

void bmatrix()
{
     for (i=1; i<=n; i++)
         for (j=1; j<=m; j++)
         {
            d[i][j]=0;
            if (a[i][j]==0)
            {
                if (d[i][j-1]!=0) d[i][j]=d[i][j-1]+1;
                else d[i][j]=1;
            }
            c[i][j][1]=d[i][j];
         }
     
     for (k=2; k<=n; k++)
         for (i=1; i<=n; i++)
             for (j=1; j<=m; j++)
             if (i-k+1>0 && a[i-k+1][j]==0)
             {
                 min=c[i][j][k-1];
                 if (d[i-k+1][j]<min) min=d[i-k+1][j];
                 c[i][j][k]=min;
             }
     
     op++;
     calc_v();
     calc_o();
}

int main()
{
    freopen("bmatrix.in","r",stdin);
    freopen("bmatrix.out","w",stdout);
    
    scanf("%d %d",&n,&m);
    for (i=1; i<=n; i++)
    {
        scanf("%s",s+1);
        for (j=1; j<=m; j++)
        {
            a[i][j]=s[j]-48;
            b[i][j]=a[i][j];
        }
    }
    
    bmatrix();
    
    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++)
            a[i][j]=b[n-i+1][m-j+1];
    
    bmatrix();
    
    max=0;
    for (i=0; i<=m; i++)
        if (l[i]+r[m-i]>max) max=l[i]+r[m-i];

    for (i=0; i<=n; i++)
        if (up[i]+down[n-i]>max) max=up[i]+down[n-i];
    
    printf("%d\n",max);
        
    return 0;    
}