program MayLava;
var
 a:array[1..11,1..11]of longint;
 m,n,sum:longint;
procedure start;
 var
  f:text;
  i,j:longint;
 begin
  fillchar(a,sizeof(a),0);
  assign(f,'number.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);
  sum:=maxlongint;
 end;
procedure hunt(x,y,z:longint);
 begin
  if (x>m) or (y>n) then exit;
  if (x=m) and (y=n) then begin
   if (z>0) and (z<sum) then sum:=z;
   exit;
  end;
  hunt(x+1,y,z+a[x+1,y]);
  hunt(x,y+1,z+a[x,y+1]);
 end;
procedure print;
 var
  f:text;
 begin
  assign(f,'number.out');
  rewrite(f);
  if sum=maxlongint then writeln(f,'-1')
  else writeln(f,sum);
  close(f);
 end;
BEGIN
 start;
 hunt(1,1,a[1,1]);
 print;
END.