ll@n,d[2n+2]{};
char@s[2n];
rep(i,2n){
	ll@a;
	rrep(j,0,i+2,2){
		d[j]=ll_inf;
		if(j>0){
			d[j]<?=d[j-1]+(s[i]=='('?0:a);
		}
		if(j<i+1){
			d[j]<?=d[j+1]+(s[i]=='('?a:0);
		}
	}
}
wt(d[0]);