// The code compiles and works fine. (It expects Ctrl+Z to stop user's input).

#include <iostream>
#include <math.h>
#include <vector>
#include <stdio.h>
using namespace std;

int main(){
        unsigned long long  a;
    vector<unsigned long long> b;
    cin.clear();
    while (cin >> a, !cin.eof()) {
        b.push_back(a);
    }

    for (vector<unsigned long long>::reverse_iterator it = b.rbegin(); it != b.rend(); ++it){
        printf("%.4f\n", sqrt((long double)*it));

    }

    return 0;

}

x   Y       u

x   Y       u

#include <iostream>
#include <math.h>
#include <vector>
#include <stdio.h>
using namespace std;

int main(){
        unsigned long long  a;
    vector<unsigned long long> b;
    cin.clear();
    while (cin >> a ) {
        b.push_back(a);
        if (cin.eof()) break;
    }

    for (vector<unsigned long long>::reverse_iterator it = b.rbegin(); it != b.rend(); ++it){
        printf("%.4f\n", sqrt((long double)*it));

    }

    return 0;

}