var

i,j,k,n,m,p,q:longint;

b,t:array[-10..1000,-10..1000] of longint;

a,x,y:array[-10..100000] of longint;

procedure kuaipai(m,n:longint);

var

i,j,k,q:longint;

begin

i:=m;

j:=n;

k:=a[(n+m) div 2];

repeat

begin

while a[i]<k do inc(i);

while a[j]>k do dec(j);

if i<=j then

begin

q:=a[i];a[i]:=a[j];a[j]:=q;

q:=x[i];x[i]:=x[j];x[j]:=q;

q:=y[i];y[i]:=y[j];y[j]:=q;

inc(i);

dec(j);

end;

end;

until i>j;

if j>m then kuaipai(m,j);

if i<n then kuaipai(i,n);

end;

begin

readln(n,m);

k:=0;

for i:=1 to n do

for j:=1 to m do

begin

inc(k);

read(a[k]);

b[i,j]:=a[k];

x[k]:=i;

y[k]:=j;

end;

kuaipai(1,n*m);

for i:=0 to n+1 do

for j:=0 to m+1 do

t[i,j]:=0;

for i:=1 to m*n do

begin

p:=x[i];

q:=y[i];

k:=1;

if (k<t[p+1,q]+1) and (a[i]>b[p+1,q]) then k:=t[p+1,q]+1;

if (k<t[p-1,q]+1) and (a[i]>b[p-1,q]) then k:=t[p-1,q]+1;

if (k<t[p,q+1]+1) and (a[i]>b[p,q+1]) then k:=t[p,q+1]+1;

if (k<t[p,q-1]+1) and (a[i]>b[p,q-1]) then k:=t[p,q-1]+1;

t[p,q]:=k;

end;

k:=1;

for i:=1 to n do

for j:=1 to m do

if k<t[i,j] then k:=t[i,j];

writeln(k);

end.