$n=<>;
@ab=<>;
for(@ab){
	($a,$b)=glob;
	$sa+=$a;
	$sb+=$b;
}
for(@ab){
	($a,$b)=glob;
	$x=$a+$b-$sb; $x=0 if $x<0; $mina=$x if $mina<$x;
	$x=$a+$b-$sa; $x=0 if $x<0; $minb=$x if $minb<$x;
}
$sa-=$mina-1;
$sb-=$minb-1;
print $sa<$sb?$sa:$sb;