#include<bits/stdc++.h>
using namespace std;

double mysqrt(double x){
	double L=0,R=x;
	while (R-L>0.000001){
		double M=(L+R)/2;
		if (M*M>x) R=M;
		else L=M;
	}
	return L;
}
int main(){
	//solve sqrt(x) 精度0.0001
	double x = 39;
	
	    cout<<fixed<<setprecision(8)<<mysqrt(x)<<endl;
	    
	    return 0;
}