coj--1196

#include<iostream>
#include<queue>
#include<cstring>
using namespace std;

int map[110][110],n,m,visited[110][110],M;
int x[]={1,0,0},y[]={0,-1,1};

typedef struct 
{
     int x,y; 
}Node;

queue<Node>q;
Node node;
void bfs()
{
    int x1,y1,x2,y2;
    while(!q.empty())
    {
        x1=q.front().x;
        y1=q.front().y;
        if(x1>M)
          M=x1;
        q.pop();
        for(int k=0;k<3;k++)
        {
            x2=x1+x[k];y2=y1+y[k];
            if(x2>=1&&x2<=n&&y2>=1&&y2<=m&&map[x2][y2]&&!visited[x2][y2])
            {
                node.x=x2;node.y=y2;
                if(x2>M) M=x2; 
                visited[x2][y2]=1;
                q.push(node);
            }
        } 
    }
}

int main()
{
    int i,j,k;
    while(cin>>n>>m)
    {
       for(i=n;i>=1;i--)
          for(j=m;j>=1;j--)
             cin>>map[i][j];
       memset(visited,0,sizeof(visited));
       M=0;
       for(i=1;i<=m;i++)
       {
           if(map[1][i])
           {
              node.x=1;
              node.y=i;
              q.push(node);
              M=1;
           }
       }
       bfs();
       cout<<M<<endl;
    }
  return 0;
}