class Interval {
    int buy;
    int sell;
}

class Solution{
    //Function to find the days of buying and selling stock for max profit.
    ArrayList<ArrayList<Integer> > stockBuySell(int A[], int n) {
        
        ArrayList<ArrayList<Integer> > result = new ArrayList<ArrayList<Integer> >();
      //Prices must be given for at least two days else return the empty result.
        if(n==1){
            return result;
        }
        
        //Creating solution vector.
        ArrayList<Interval> sol = new ArrayList<Interval>();
        int i=0, cnt=0;
        //Traversing through given price array.
        while (i < n-1) {
            //Finding Local Minima. Note that the limit of loop is (n-2)
            //as we are comparing present element to the next element.
            while ((i < n-1) && (A[i+1] <= A[i])){
                i++;
            }
            //If we reach the end, we break loop as no further 
            //solution is possible.
            if (i == n-1){
                break;
            }
            Interval e = new Interval();
            //Storing the index of minima which gives the day of buying stock.
            e.buy = i++;
 
            //Finding Local Maxima. Note that the limit of loop is (n-1)
            //as we are comparing present element to previous element.
            while ((i < n) && (A[i] >= A[i-1]))
                i++;
 
            //Storing the index of maxima which gives the day of selling stock.
            e.sell = i-1;
            sol.add(e);
            //Incrementing count of buy/sell pairs.
            cnt++;
        }
        if(cnt==0){
            return result;
        } else {
            //Storing the buy/sell pairs in a list.
            for(int j=0; j<sol.size(); j++){
                result.add(new ArrayList<Integer>()); 
                result.get(j).add(0, sol.get(j).buy);
                result.get(j).add(1, sol.get(j).sell);
            }
        }
        //returning the result.
        return result;
    } 
    
}