program light;
var
  i,j,k:longint;
  n,m:longint;
  a:array[1..10000000]of boolean;
  o:extended;
begin
  assign(input,'light.in');
  reset(input);
  assign(output,'light.out');
  rewrite(output);
  readln(n);
  for i:=1 to n do
  begin
    readln(o,m);
    for j:=1 to m do
    begin
      if o*j>10000000 then break;
      k:=trunc(o*j);
      a[k]:=not a[k];
    end;
  end;
  for i:=1 to 10000000 do
    if a[i] then
    begin
      writeln(i);
      break;
    end;
  close(input);
  close(output);
end.