($m,$ans)=glob<>;
$_=<>;
0while
s{(\w+)|(&)\B(?![(])|(\$)\B(?![&(])|(\(\))}{
	if(defined$1){
		push@a,{$1,$1};
	}
	if($2|$3){
		$b=pop@a;
		$a=pop@a;
		push@a,$r={};
		for$x(keys%$a){
			$u=$$a{$x};
			for$y(keys%$b){
				$v=$$b{$y};
				if($2){
					if($y!=0){
						$$r{int$x/$y}="$u/$v";
					}
					if($x*$y<=$m){
						$$r{$x*$y}="$u*$v";
					}
				}
				if($3){
					if($x-$y>=0){
						$$r{$x-$y}="$u-$v";
					}
					if($x+$y<=$m){
						$$r{$x+$y}="$u+$v";
					}
				}
			}
		}
	}
	if($4){
		for(values%{$a[-1]}){
			$_="($_)";
		}
	}
}e;
print$a[0]{$ans}||-1,$/;