#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
    const unsigned int N=32768;
    unsigned long long xl[N];
    unsigned int col=0;
    cin.setf(ios::skipws);
    while(cin>>xl[col]) col++;
    cout.unsetf(cout.flags());
    cout.setf(ios::showpoint|ios::fixed|ios::dec);
    while(col--) cout<<setprecision(4)<<sqrt((double)xl[col])<<endl;
    return 0;
}

Decided. Please explain some of the time, please.

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
typedef unsigned long long Beta;
int main()
{
    const unsigned int N=128*1024;
    Beta *xl=new Beta[N];
    int col=0;
    cin.setf(ios::skipws);
    while(cin>>xl[col]) col++;
    cout.unsetf(cout.flags());
    cout.setf(ios::showpoint|ios::fixed|ios::dec);
    while(col--) cout<<setprecision(4)<<sqrt((double)xl[col])<<endl;
    delete []xl;
    return 0;
}

The size of the input stream 256 kb.
So we need to allocate memory in the amount of (256*1024)/sizeof(_int64);
Why is the correct decision should be 128 * 1024?