program joc_flip;   
var f:text;   
    a:array[1..20,1..20]of longint;   
    st:array[0..100]of longint;   
    i,j,m,n,h,q:longint;   
    s,s1,max,suma:longint;   
    as:boolean;   
begin  
assign(f,'flip.in');reset(f);   
readln(f,m,n);   
for i:=1 to m do  
    begin  
    for j:=1 to n do  
        read(f,a[i,j]);   
    readln(f);   
    end;   
close(f);   
max:=-2000000000;   
j:=1;   
st[j]:=-1;   
while j>0 do  
      begin  
      if st[j]<1 then begin  
                      st[j]:=st[j]+1;   
                      as:=true;   
                      end  
                  else as:=false;   
      if as then begin  
                 if j=m then begin  
                             for i:=1 to m do  
                                 if st[i]=0 then for h:=1 to n do  
                                                     a[i,h]:=a[i,h]*(-1);   
                             suma:=0;   
                             for i:=1 to n do  
                                 begin  
                                 s:=0;   
                                 for h:=1 to m do  
                                     s:=s+a[h,i];   
                                 if s>0 then suma:=suma+s   
                                         else suma:=suma-s;   
                                 end;   
                             if suma>max then max:=suma;   
                             end ; 
                          
                 end  
            else begin  
                 j:=j-1;   
                 if st[j]=0 then for i:=1 to n do  
                                     a[j,i]:=a[j,i]*(-1);   
                 end;   
      end;   
assign(f,'flip.out');rewrite(f);   
writeln(f,max);   
close(f);   
end.