#include <iostream>
#include <iomanip>
#include <cmath>
#include <vector>

using namespace std;

int main() {
    cout << setprecision(4);
    vector<double> v;
    double n;
    while (cin >> n)
        v.push_back(n);
    for (int i = v.size() - 1; i >= 0; i--)
        cout << sqrt(v[i]) << endl;
}

WA1 typically means your program can't even pass the task example.
Let's see your: https://ideone.com/Y8Uxei - yes, output is wrong.