#include<stdio.h>
int n,m;
int x1[4]={0,0,1,-1},y1[4]={1,-1,0,0};
int hill[105][105]={0};
int height[105][105]={0};
int maxs=0;
void ss(int x,int y,int len)
{
    height[x][y]=len;
    if(len>maxs)maxs=len;
    for(int i=0;i<4;i++)
    {
        int x2=x+x1[i],y2=y+y1[i];
        if(hill[x2][y2]<=hill[x][y]&&x2>=1&&x2<=n&&y2>=1&&y2<=m&&len+1>height[x2][y2])ss(x2,y2,len+1);
    }

}
int main()
{

    scanf("%d%d",&n,&m);


    for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)scanf("%d",&hill[i][j]);

    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            int tallest=1;
            for(int l=0;l<4;l++)
            {
                int x2=i+x1[l],y2=j+y1[l];
                if(x2>=1&&x2<=n&&y2>=1&&y2<=m)
                if(hill[i][j]<hill[x2][y2]||height[x2][y2]>=2)tallest=0;
            }
            if(tallest) ss(i,j,1);
        }
        printf("%d",maxs);
        return 0;
}