program balance;
type
fxz1=array[0..50000] of longint;
var
dd,d,a:fxz1;
f1,f2:text;
i,j,n,m:longint;
procedure qsort(left,right:longint);
  var
   l,r,x,y:longint;
  begin
   l:=left; r:=right; x:=a[(l+r) div 2];
   repeat
    while a[l]<x do inc(l);
    while a[r]>x do dec(r);
    if l<=r then
     begin
      y:=a[l];
      a[l]:=a[r];
      a[r]:=y;
      y:=d[l];
      d[l]:=d[r];
      d[r]:=y;
      inc(l); dec(r);
     end;
   until l>r;
   if l<right then qsort(l,right);
   if r>left then qsort(left,r);
  end;




begin assign(f1,'balance.in');
      assign(f2,'balance.out');
      reset(f1);rewrite(f2);
      readln(f1,n);
      for i:=1 to n do
      begin readln(f1,d[i],a[i]);
            inc(dd[d[i]]);
      end;
      qsort(1,n);
      if dd[0]=dd[1] then writeln(f2,a[n]-a[1])
                   else writeln(f2,'1000000000');
      close(f1);close(f2);
end.