#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
double a,s;
cin>>a;
s=a*0.05;
if(s<5&&s>0)s=5;
else s=a*0.05;
cout<<fixed<<setprecision(2)<<a-s;
return 0;
}

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
double a,s;
cin>>a;
s=a*0.05;
if(s<5&&s>0)s=5;
else s=a*0.05;
cout<<fixed<<setprecision(2)<<a-s;
return 0;
}

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    double m,t;
    cin>>m;
    t=m*0.05;
    if(t<5)
        cout<<fixed<<setprecision(2)<<m-5*1.0;
    else  
        cout<<fixed<<setprecision(2)<<m-t;
    return 0;
}