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

double mysprt(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 sprt(x) 精度0.0001
	double x=39;
	
	 cout<<fixed<<setprecision(8)<<mysprt(x)<<endl;
	 
	 return 0;
}

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

int main() {
	int n;
	cin>>n;
	int phi = n;
	for (int i=2; i*i<=n; i++) {
		if (n%i==0) {
			phi = phi / i * (i-1);
			while (n % i==0) n = n / i;
		}
	}
	if (n>1) phi = phi / n * (n-1);
	cout<<phi<<endl;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    long long n;
    while(cin>>n){
        long long ans=n;
        ans-=n/2+n/5+n/11+n/13;
        ans+=n/(2*5)+n/(2*11)+n/(2*13)+n/(5*11)+n/(5*13)+n/(11*13);
        ans-=n/(2*5*11)+n/(2*5*13)+n/(2*11*13)+n/(5*11*13);
        ans+=n/(2*5*11*13);
        cout<<ans<<endl;
    }
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    double L=1.5, R=2.4;
    while (R-L>0.00000001){
        double M=(L+R)/2;
        //L,R 分成  左边L~~M  右边M~~R
        //if (f(L)*f(M)<0  在zuobian) R=M;

        if ((L*L*L*L*L-15*L*L*L*L+85*L*L*L-225*L*L+274*L-121)*(M*M*M*M*M-15*M*M*M*M+85*M*M*M-225*M*M+274*M-121)<0)
            R=M;
        else
            L=M;
    }
    cout<<fixed<<setprecision(6)<<L<<endl;
    return 0;
}

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

using namespace std;

int main()
{
double a,b,c,d,x1,x2;
cin>>a>>b>>c>>d;
x1=(-a+sqrt(a*a-4*b))/2;
x2=(-a-sqrt(a*a-4*b))/2;
if ((c<x1 && x1<d) || (d<x1 && c>x1))
{
cout<<fixed<<setprecision(6)<<x1;
}
else
{
cout<<fixed<<setprecision(6)<<x2;
}
return 0;
}

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

int a[20];
int main(){
    int n=10;
    for (int i=1;i<=n;i++) cin>>a[i];

    for(int i=1;i<=n;i++)
        if(a[i]%2==1) a[i]=-a[i];

    for (int i=1;i<=n;i++) {
        int k=i;
        for (int j=i;j<=n;j++)
            if(a[j]<a[k]) k=j;
            swap(a[i],a[k]);
    }

    for(int i=1;i<=n;i++) if (abs(a[i])%2==1) cout<<-a[i]<<" ";

    for(int i=1;i<=n;i++) if (a[i]%2==0) cout<<a[i]<<" ";
}

#include <bits/stdc++.h>
using namespace std;
int b[10000005],prime[10000005];
void SF(int n) {
	int cnt=0;
	for (int i=2;i<=n;i++) {
		if (b[i]==0) {
			cnt++; prime[cnt]=i;
			for(int j=2*i;j<=n;j=j+i) {
				b[j]=1;
			}
		}
	}
	
	cout<<endl;
	cout<<n<<" "<<cnt<<endl;
}
int main(){
	SF(10000000);
	return 0;
}