program xxxx;
var f:array[1..2000000] of boolean;
    n,i,j,ti:longint;
    ai:real;
begin
  assign(input,'light.in');
  reset(input);
  assign(output,'light.out');
  rewrite(output);
  read(n);
  for i:=1 to 2000000 do
    f[i]:=false;
  for i:=1 to n do
    begin
      read(ai,ti);
      for j:=1 to ti do
        if f[trunc(ai*j)] then
          f[trunc(ai*j)]:=false
        else
          f[trunc(ai*j)]:=true;
    end;
  for i:=1 to 2000000 do
    if f[i] then
      begin
        write(i);
        break;
      end;
  close(input);
  close(output);
end.