$t=<>;
($x,$a)=glob<>;
($y,$b)=glob<>;
if($t<0){
	$q=int+(1-$t)/$b+1;
	$c+=$q*$y;
	$t+=$q*$b;
}
{
	$q=int$t/$a;
	$c+=$q*$x;
	$t-=$q*$a;
	$d=$c+$t;
}
while(1){
	$t+=$y;
	$c+=$b;
	$q=int$t/$a;
	$c+=$q*$x;
	$t-=$q*$a;
	if($c>$d){
		last;
	}
	if($d>$c+$t){
		$d=$c+$t;
	}
}
print$d;