#include<bits/stdc++.h> using namespace std; int main(){
long double f; cin>>f; cout<<fixed<<setprecision(5)<<5.0*(f-32)/9.0; return 0; }

#include <bits/stdc++.h> using namespace std; int main(){ int a; cin>>a; cout<<fixed<<setprecision(5)<<5.0*(a-32.0)/9.0; return 0; }