#https://github.com/shakayami/ACL-for-python/blob/master/segtree.py
class segtree():
    n=1
    size=1
    log=2
    d=[0]
    op=None
    e=10**15
    def __init__(self,V,OP,E):
        self.n=len(V)
        self.op=OP
        self.e=E
        self.log=(self.n-1).bit_length()
        self.size=1<<self.log
        self.d=[E for i in range(2*self.size)]
        for i in range(self.n):
            self.d[self.size+i]=V[i]
        for i in range(self.size-1,0,-1):
            self.update(i)
    def set(self,p,x):
        assert 0<=p and p<self.n
        p+=self.size
        self.d[p]=x
        for i in range(1,self.log+1):
            self.update(p>>i)
    def get(self,p):
        assert 0<=p and p<self.n
        return self.d[p+self.size]
    def prod(self,l,r):
        assert 0<=l and l<=r and r<=self.n
        sml=self.e
        smr=self.e
        l+=self.size
        r+=self.size
        while(l<r):
            if (l&1):
                sml=self.op(sml,self.d[l])
                l+=1
            if (r&1):
                smr=self.op(self.d[r-1],smr)
                r-=1
            l>>=1
            r>>=1
        return self.op(sml,smr)
    def all_prod(self):
        return self.d[1]
    def max_right(self,l,f):
        assert 0<=l and l<=self.n
        assert f(self.e)
        if l==self.n:
            return self.n
        l+=self.size
        sm=self.e
        while(1):
            while(l%2==0):
                l>>=1
            if not(f(self.op(sm,self.d[l]))):
                while(l<self.size):
                    l=2*l
                    if f(self.op(sm,self.d[l])):
                        sm=self.op(sm,self.d[l])
                        l+=1
                return l-self.size
            sm=self.op(sm,self.d[l])
            l+=1
            if (l&-l)==l:
                break
        return self.n
    def min_left(self,r,f):
        assert 0<=r and r<=self.n
        assert f(self.e)
        if r==0:
            return 0
        r+=self.size
        sm=self.e
        while(1):
            r-=1
            while(r>1 and (r%2)):
                r>>=1
            if not(f(self.op(self.d[r],sm))):
                while(r<self.size):
                    r=(2*r+1)
                    if f(self.op(self.d[r],sm)):
                        sm=self.op(self.d[r],sm)
                        r-=1
                return r+1-self.size
            sm=self.op(self.d[r],sm)
            if (r& -r)==r:
                break
        return 0
    def update(self,k):
        self.d[k]=self.op(self.d[2*k],self.d[2*k+1])
    def __str__(self):
        return str([self.get(i) for i in range(self.n)])
n = int(input())
if n % 2 == 1:
    exit(print(-1))
s = list(input().rstrip())
z = 0
l,r = s.count('('),s.count(')')
o = 0
c = abs(l-r)//2
if l > r:
    z = 0
    o = 1

else:
    z = -(r-l)//2
r,m = map(int,input().split())
t = s[:] + s[:]
a = [1 if i == '(' else -1 for i in t]
import itertools
b = list(itertools.accumulate(a))
st = segtree(b,min,10**18)
b.append(0)
ans = 10**18
if o:
    for i in range(n):
        i#f o:break
        temp = (n - i) * r
        if i== 0:
            temp = 0
        x = st.prod(i,i+n)
        x -= b[i-1]
        
        temp += c * m
        
        #print(i,x,z,t[i:i+n],temp,c)
        if x < 0:
            x *= -1
            temp += ((x//2) + (x % 2)) * m*2
        ans = min(ans,temp)

        
#(()((())))
for i in range(n):
    if o:break
    temp = (n - i) * r
    if i== 0:
        temp = 0
    x = st.prod(i,i+n)
    x -= b[i-1]
    x = b[n-1+i]-b[i-1] - x
    #print(i,x,z,t[i:i+n],temp,c)
    
    #x *= -1
    
    y = x // 2 + (x % 2)
    #y = min(y,c)
    temp += y * m * 2
    x -= 1 * y

    temp += c * m
    #print(temp)
    ans = min(ans,temp)
print(ans)