#include<cstdio>


int main(void)
{
	int n, k, i, f, d;
	char s[10000+2];

	while(scanf("%d%d\n", &n, &k)==2)
	{
		scanf("%[()]", s);

		if(s[k-1]=='(') d= 1;
		else            d=-1;

		f=d;
		for(i=k-1+d;i<n && i>=0;i+=d)
		{
			if(s[i]=='(') f++;
			if(s[i]==')') f--;
			if(f==0) break;
		}
		printf("%d\n", i+1);
	}
	return 0;
}