#include <stdio.h>


int main(void) {
	int n,k,i,count=0;
	char s[10000],c;

	scanf("%d %d %s",&n,&k,&s);

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

}