var n,m,i,k,x,y,d,l,st:longint;
    A:array [0..20,0..20] of longint;
BEGIN
read(n,m);
          for i:=1 to n do
          begin
              for k:=1 to m do
              read(A[i,k]);
          writeln();
          end;
          for i:=1 to n do
              for k:=1 to m do
              begin
                   if (A[i+1,k]=0) then
                   d:=A[i,k+1]+A[i,k]
                   else
                   begin
                   if (A[i+1,k]>A[i,k+1]) then
                   d:=A[i,k+1]+A[i,k]
                   else
                   d:=A[i+1,k]+A[i,k];
                   if (A[i,k+1]=0) then
                   d:=A[i+1,k]+A[i,k]
                   else
                   begin
                   if (A[i+1,k]>A[i,k+1]) then
                   d:=A[i,k+1]+A[i,k]
                   else
                   d:=A[i+1,k]+A[i,k];
                   end;
                   end;
              end;
writeln(d);
END.