### BUGGY CODE ###

# Max演算に絞ったsegment treeでもpython3だとTLE？

class SegmentTreeMax:
    def __init__(self, a):
        self.padding =  -float('inf')
        
        n = len(a)
        self.N = 2 ** (n-1).bit_length()
        self.data = [self.padding]*(self.N-1) + a + [self.padding]*(self.N-n)
        for i in range(2*self.N-2, 0, -2):
            self.data[(i-1)//2] = max(self.data[i], self.data[i-1])
    
    def update(self, idx, x):
        idx = self.N - 1 + idx
        self.data[idx] = x
        while idx:
            idx = (idx-1) // 2
            self.data[idx] = max(self.data[2*idx+1], self.data[2*idx+2])
    
    def search(self, i, j):
        # [i, j)の区間の最小値を求める
        idx1 = self.N-1+i
        idx2 = self.N-1+j-1
        result = self.padding
        while idx1 + 1 < idx2:
            if idx1&1 == 0: # idx1が偶数
                result = max(result, self.data[idx1])
            if idx2&1 == 1: # idx2が奇数
                result = max(result, self.data[idx2])
                idx2 -= 1
            
            idx1 //= 2
            idx2 = (idx2 - 1)//2
        
        if idx1 == idx2:
            result = max(result, self.data[idx1])
        else: # idx1 + 1 == idx2
            result = max(result, self.data[idx1], self.data[idx2])
        
        return result


N = int(input())
H = list(map(int, input().split()))
A = list(map(int, input().split()))

dp = [0] * (N+1)
st = SegmentTreeMax(dp)

ans = 0
for h, a in zip(H, A):
  M = st.search(0, h)
  st.update(h, M + a)

print(st.search(0, N+1))

### FIXED CODE ###

class SegmentTree:
    def __init__(self, a, mode='min'):
        self.mode = mode
        if self.mode == 'min':
            self.padding = float('inf')
        elif mode == 'max':
            self.padding = -float('inf')
        elif mode == 'sum':
            self.padding = 0
        
        n = len(a)
        self.N = 2 ** (n-1).bit_length()
        self.data = [self.padding]*(self.N-1) + a + [self.padding]*(self.N-n)
        for i in range(2*self.N-2, 0, -2):
            self.data[(i-1)//2] = self._segfunc(*[self.data[i], self.data[i-1]])
    
    def _segfunc(self, *v_list):
        if self.mode == 'min':
            return min(v_list)
        elif self.mode == 'max':
            return max(v_list)
        elif self.mode == 'sum':
            return sum(v_list)
    
    def update(self, idx, x):
        idx = self.N - 1 + idx
        self.data[idx] = x
        while idx:
            idx = (idx-1) // 2
            self.data[idx] = self._segfunc(
                *[self.data[2*idx+1], self.data[2*idx+2]]
            )
    
    def search(self, i, j):
        # [i, j)の区間の最小値を求める
        idx1 = self.N-1+i
        idx2 = self.N-1+j-1
        result = self.padding
        while idx1 + 1 < idx2:
            if idx1&1 == 0: # idx1が偶数
                result = self._segfunc(*[result, self.data[idx1]])
            if idx2&1 == 1: # idx2が奇数
                result = self._segfunc(*[result, self.data[idx2]])
                idx2 -= 1
            
            idx1 //= 2
            idx2 = (idx2 - 1)//2
        
        if idx1 == idx2:
            result = self._segfunc(result, self.data[idx1])
        else: # idx1 + 1 == idx2
            result = self._segfunc(*[result, self.data[idx1], self.data[idx2]])
        
        return result


N = int(input())
H = list(map(int, input().split()))
A = list(map(int, input().split()))

dp = [0] * (N+1)
st = SegmentTree(dp, mode='max')

ans = 0
for h, a in zip(H, A):
  M = st.search(0, h)
  st.update(h, M + a)

print(st.search(0, N+1))