def solve():
    N, S = map(int, input().split())
    X = list(map(int, input().split()))
    W = list(map(int, input().split()))
    
    # Sより左と右に分ける
    left = []   # Sに近い順（xが大きい順）
    right = []  # Sに近い順（xが小さい順）
    
    for i in range(N):
        if X[i] < S:
            left.append((X[i], W[i]))
        else:
            right.append((X[i], W[i]))
    
    left.sort(reverse=True)  # Sに近い順
    right.sort()              # Sに近い順
    
    L, R = len(left), len(right)
    total_weight = sum(W)
    
    # 累積和（配達済み重量の計算用）
    left_sum = [0] * (L + 1)
    for i in range(L):
        left_sum[i + 1] = left_sum[i] + left[i][1]
    
    right_sum = [0] * (R + 1)
    for j in range(R):
        right_sum[j + 1] = right_sum[j] + right[j][1]
    
    INF = float('inf')
    dp = [[[INF] * 2 for _ in range(R + 1)] for _ in range(L + 1)]
    dp[0][0][0] = dp[0][0][1] = 0
    
    for i in range(L + 1):
        for j in range(R + 1):
            for d in range(2):
                if dp[i][j][d] == INF:
                    continue
                
                # 現在位置
                if i == 0 and j == 0:
                    cur_pos = S
                elif d == 0:
                    cur_pos = left[i - 1][0]
                else:
                    cur_pos = right[j - 1][0]
                
                # 残り重量
                remaining = total_weight - left_sum[i] - right_sum[j]
                
                # 左に進む
                if i < L:
                    dist = abs(cur_pos - left[i][0])
                    dp[i + 1][j][0] = min(dp[i + 1][j][0], dp[i][j][d] + dist * remaining)
                
                # 右に進む
                if j < R:
                    dist = abs(cur_pos - right[j][0])
                    dp[i][j + 1][1] = min(dp[i][j + 1][1], dp[i][j][d] + dist * remaining)
    
    print(min(dp[L][R][0], dp[L][R][1]))

solve()