n,k = map(int,input().split())
s = list(input())
stk = []
numl = []
for idx,itm in enumerate(s) :
    if itm == "(":
        stk.append((itm,idx+1))
        numl.append((itm,idx+1))
    elif itm == ")" :
        numl.append((itm,stk[-1][-1]))
        stk.pop()
if numl[k-1][0] == "(":
    print(numl.index((")",numl[k-1][1]))+1)
elif numl[k-1][0] == ")":
    print(numl.index(("(",numl[k-1][1]))+1)