public int maxProfit(int[] prices) {
		 if(prices == null || prices.length == 0){
			 return 0;
		 }
		 int res = 0;
		 for(int i = 1; i <=  prices.length-1 ;i++){
			 if(prices[i-1] < prices[i]){
				 res += prices[i]-prices[i-1];
			 }
		 }
		 return res;
	 }