var
  n,t,i,z,min,j,max:longint;
  s:real;
  f:array[0..20000000]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(s,t);
    for j:=1 to t do
    begin
      z:=trunc(j*s);
      if not f[z] then f[z]:=true
      else f[z]:=false;
      if z>max then max:=z;
      if z<min then min:=z;
    end;
  end;
  for i:=min to max do
  if f[i] then
  begin
    writeln(i);
    break;
  end;
  close(input);
  close(output);
end.