#include <iostream>

#include <cmath>

#include <iomanip>
using namespace std;

int main()
{
    const int U=100000;
    double A[U]={0};
    int b=0;


        while(cin>>A[b])
        b++;
    for(int c=U-1;c>=0;c--)
    {

        {double root2 = sqrt( A[c] );

cout.setf( std::ios::fixed,std:: ios::floatfield );

        cout<<root2;
    cout<<"\n";
        }
    }
    return 0;
}

pay attention to start point of loop:
    for(int c=b-1;c>=0;c--)

and set precision of cout:
    cout.precision(4);