program light(input,output);

const
  maxl=2000010;

var
  a:double;
  n,t,i,j,tr:longint;
  boo:array[1..maxl]of boolean;

begin
  assign(input,'light.in');
  reset(input);
  assign(output,'light.out');
  rewrite(output);

  readln(n);
  for i:=1 to n do
  begin
    readln(a,t);

    for j:=1 to t do
    begin
      tr:=trunc(a*j);

      if tr>maxl then
        break;

      boo[tr]:=not boo[tr];
    end;
  end;

  for i:=1 to maxl do
    if boo[i] then
    begin
      writeln(i);
      break;
    end;

  close(input);
  close(output);
end.