#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
vector< vector<int> > v(12, vector<int>(12,0));
int RECU(int i, int j){
if ( j>0 && j<=10 && i>0 && i<=10 ){
if (v[i][j-1] ==1) { v[i][j-1] = 0; return 1+RECU(i,j-1); }
if (v[i][j+1] ==1) { v[i][j+1] = 0; return 1+RECU(i,j+1); }
if (v[i+1][j] ==1) { v[i+1][j] = 0; return 1+RECU(i+1,j); }
if (v[i-1][j] ==1) { v[i-1][j] = 0; return 1+RECU(i-1,j); }
if (v[i-1][j-1] ==1) { v[i-1][j-1] = 0; return 1+RECU(i-1,j-1); }
if (v[i-1][j+1] ==1) { v[i-1][j+1] = 0; return 1+RECU(i-1,j+1); }
if (v[i+1][j-1] ==1) { v[i+1][j-1] = 0; return 1+RECU(i+1,j-1); }
if (v[i+1][j+1] ==1) { v[i+1][j+1] = 0; return 1+RECU(i+1,j+1); }
}
return 0;
}
int main() {
int m,n,i,j;
cin>>m>>n;
for (i=1;i<=m;i++)
for (j=1;j<=n;j++){
cin>>v[i][j];
}
int Max=-1, max=-1;
for (i=1;i<=m;i++)
for (j=1;j<=n;j++){
if (v[i][j]==1) {v[i][j]=0; max=1+RECU(i,j);}
if (max>Max) Max=max;
}
cout <<Max;
return 0;
}
