N,K=map(int,input().split())
S=input()
L=[]
A=0
for i in range(N):
    L.append([S[i],i+1])
for j in range(N):
    for i in range(len(L)):
        if L[i][0]=="(" and L[i+1][0]==")":
            if L[i][1]==K:
                A=L[i+1][1]
            elif L[i+1][1]==K:
                A=L[i][1]
            else:
                del L[i]
                del L[i]
                break
print(A)