#include <stdio.h>
#include <stdlib.h>

int main()
{
        int K, N;
        char *kakko ;
        int i;
        int cnt;
        scanf("%d %d\n", &N, &K );

        kakko = (char *)malloc(sizeof(char)*N+1+1);
        scanf("%s\n", kakko+1);



        int idou;
        char my, you;
        if( kakko[K] == '(' ) {
                i = K+1;
                idou = 1;
                my = '(';
                you = ')';
        }
        else {
                i = N-1;
                idou = -1;
                my = ')';
                you = '(';
        }
        cnt = 1;
        while( cnt != 0) {
                if( kakko[i] == my ) {
                        cnt++;
                }
                else if( kakko[i] == you ) {
                        cnt--;
                }
                i += idou;
        }
        printf("%d\n", i-idou );
        return 0;
}