My program uses only 850K of memory!!!
Two days of troubles and the best solution was written!
If you are intrested in it leave your mail here.

I've solved this problem via interval tree, but it uses 4 Mbytes. I don't need your code, but could you explain your algorithm? My e-mail is dimanyes@yahoo.com

I think, that he have used Fenwick tree

No :)
This solution uses Cartesian tree.
My best solution which uses Fenwick's tree uses
about 1400K of memory

PS: Good luck on the ROI, Ilya :)

I've modified this solution...
Now it uses only 630K of memory!!!
(Random Trees are very useful :)

Can you say book's names where these tree are described?

can i do it without trees ? like this
#include<iostream>
#include<string>
using namespace std;
void limit_to_two_num(float &price)
{
    price=price*100;
    price=static_cast<int>(price);
    price=(price)/100;
}
void main()
{
    int check=0,quantity,length=0;
    string str="\0";
    float price;
    float profit=0;
    float arr[100000];
    while(str!="QUIT" && check!=100000)
    {
        cin>>str;
        if(str=="BID")
        {
            cin>>price;
            limit_to_two_num(price);
            arr[length++]=price;
            check++;
        }
        else if(str=="DEL")
        {
            cin>>price;
            limit_to_two_num(price);
            for(int i=0;i<length;i++)
            {
                if(arr[i]==price)
                {
                    for(int j=i;j<length-1;j++)
                    {
                        arr[j]=arr[j+1];
                    }
                    length--;
                    break;
                }
            }
            check++;
        }
        else if(str=="SALE")
        {
            cin>>price;
            limit_to_two_num(price);
            cin>>quantity;
            for(int i=0;i<length;i++)
            {
                if(arr[i]>=price)
                {
                    profit=profit+0.01;
                }
            }
        }
    }
    cout<<"Total profit: "<<profit<<endl;
}

i can't solve this problem.Please help... yu1178209138@hotmail.com