import java.util.*;


public class Solution {
    public int maxProfit (int[] prices) {
        // 只进行一次买入和卖出
        int ret =0;

        //双层遍历
        int n = prices.length;
        for(int i=0;i<n;i++){
            for(int j=i;j <n;j++){
                ret = Math.max(ret,prices[j]-prices[i]);
            }
        }

        return ret;

    }
}