program 8_67;
const MaxN=10; MAxM=8;
Type Tmyarray=array[1..maxn,1..maxm] of integer;
var A:Tmyarray;
n,m,i,j,dbl:integer;
Procedure TInit(var A:Tmyarray;
Var n,m:integer);
var i,j:integer;
Begin
Readln(n,m);
for i:=1 to n do
for j:=1 to m do Read(A[i,j]);
end;
Procedure TPrint (A:TMyarray; n,m:integer);
var i,j:integer;
Begin
for i:=1 to n do begin
for j:=1 to m do
write(A[i,j]:4);
writeln;
end;
end;
BEGIN
TInit(A,n,m);
TPrint(A,n,m);
i:=0;
repeat
j:=0; Inc(i);
dbl:=0;
repeat
inc(j);
if A[i,j]<0 then inc(dbl);
Until (j=m) or (dbl>2);
Until (i=n) or (dbl=2);
if dbl=2 then writeln('yes')
else writeln('No');
End.