Memory limit exceeded    #7    time = 1.312    Memory used = 20 620 KB.
Why memory used too much???? :((


#include <iostream>
#include <math.h>
#include <iomanip>
#include <string>
#include <sstream>
using namespace std;

string d2s(double x)
{
    stringstream ii;
    ii << fixed << setprecision(4) << x;
    return ii.str();
}

int main( )
{
    double n;
        string s = "";
    while ((cin >> n))
    {
          s = d2s(sqrt(n)) + "\n" + s;
    }
    cout << s;

    return 0;
}