#include <iostream>
int st[10000],h=0,N,K;
int main(){
	std::cin>>N>>K;
	for(int i=0;i<N;i++){
		char c;
		std::cin>>c;
		if(c=='(')st[h++]=i+1;
		else if(i+1==K){std::cout<<st[h-1]<<std::endl;return 0;}
		else if(st[h-1]==K){std::cout<<i+1<<std::endl;return 0;}
		else h--;
	}
}