//DP,把高度排序后，从小到大算，每次都计算周围四个中最大的那个，是从bellman算法想
//到的，但不知道为什么错。我分别用hash和sort排序都过不了~~~
//关键是测试了近百个变态的测试数据都没有错误（递归DP的算法ac以后用来对比校验）
//第一个：sort排序
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int M,N;
int hi[1000][1000];
int st[1000][1000];

struct nod
{
    int x,y,h;
}data[11000000];

bool cmp(nod a,nod b)
{
    return a.h<b.h;
}
int main()
{

    int top;
    int i,j,k,t,max_t;
    freopen("1.txt","r",stdin);
    while (scanf("%d%d",&M,&N)!=EOF)
    {
        memset(st,0,sizeof(st));
        for(i=0;i<=M+1;++i)
            for(j=0;j<=N+1;++j)
                hi[i][j]=-1;
        top=0;
        for (i=1;i<=M;++i)
        {
            for (j=1;j<=N;++j)
            {
                scanf("%d",&t);
                data[top].x=i,data[top].y=j,data[top].h=t;
                top++;
                hi[i][j]=t;
            }
        }
        sort(data,data+top,cmp);

        for (k=0;k<top;++k)
        {
            i=data[k].x,j=data[k].y;
            max_t=st[i][j];
            if (hi[i+1][j]<hi[i][j]&&st[i+1][j]>=max_t)
                max_t=st[i+1][j]+1;
            if (hi[i-1][j]<hi[i][j]&&st[i-1][j]>=max_t)
                max_t=st[i-1][j]+1;
            if (hi[i][j+1]<hi[i][j]&&st[i][j+1]>=max_t)
                max_t=st[i][j+1]+1;
            if (hi[i][j-1]<hi[i][j]&&st[i][j-1]>=max_t)
                max_t=st[i][j-1]+1;
            st[i][j]=max_t;
        }
        max_t=1;
        for(i=1;i<=M;++i)
            for(j=1;j<=N;++j)
            {
                if(st[i][j]>max_t)
                    max_t=st[i][j];
            }
        printf("%d\n",max_t);
    }
    return 0;
}
//第二个程序，用hash拉链排序~
/*struct nod
{
    int x,y;
    int h;
    nod* next;
}Pool[110000],*hash[100100000],*p,*ma;
int main()
{
    int i,j,k,max_t;
    freopen("1.txt","r",stdin);
    while (scanf("%d%d",&M,&N)!=EOF)
    {
        memset(st,0,sizeof(st));
        memset(hash,0,sizeof(hash));
        memset(hi,0xff,sizeof(hi));
        ma=Pool;
        for (i=1;i<=M;++i)
        {
            for (j=1;j<=N;++j)
            {
                scanf("%d",&hi[i][j]);
                ma->x=i,ma->y=j;
                ma->next=hash[hi[i][j]];
                hash[hi[i][j]]=ma;
                ma++;
            }
        }
        for(k=0;k<=100000000;++k)
        {
            if(hash[k])
            {
                p=hash[k];
                while(p!=NULL)
                {
                    i=p->x,j=p->y;
                    max_t=st[i][j];
                    if (hi[i+1][j]<hi[i][j]&&st[i+1][j]>=max_t)
                        max_t=st[i+1][j]+1;
                    if (hi[i-1][j]<hi[i][j]&&st[i-1][j]>=max_t)
                        max_t=st[i-1][j]+1;
                    if (hi[i][j+1]<hi[i][j]&&st[i][j+1]>=max_t)
                        max_t=st[i][j+1]+1;
                    if (hi[i][j-1]<hi[i][j]&&st[i][j-1]>=max_t)
                        max_t=st[i][j-1]+1;
                    st[i][j]=max_t;
                    p=p->next;
                }
            }
        }
        max_t=1;
        for(i=1;i<=M;++i)
            for(j=1;j<=N;++j)
            {
                if(st[i][j]>max_t)
                    max_t=st[i][j];
            }
        printf("%d\n",max_t);
    }
    return 0;
}*/
//谢谢