#include <bits/stdc++.h>
using namespace std;
char s[10010];
int n,k,i,j,p;
int main(){
    cin>>n>>k>>s;
    i=k-1;
    while(true){
        if(s[i]=='(') ++p;
        else --p;
        if(p==0) break;
        if(s[k-1]=='(') ++i;
        else --i;
    }
    cout<<i+1<<endl;
    return 0;
}