class Solution(object):
    def maxProfit(self, prices):
        """
        :type prices: List[int]
        :rtype: int
        """
        if not prices:
         return 0
        profit = 0
        min_val = prices[0]

        for p in prices[1:]:
            if p > min_val:
                profit += p - min_val
                min_val = p
            else:
                min_val = p
        return profit