直接判。

#include<bits/stdc++.h>
//#define int long long
#define INF 0x3f3f3f
using namespace std;
double n;
signed main(){
	cin>>n;
	if(n!=int(n))n=int(n)+1;
	if(n<=5)cout<<"10";
	else cout<<(n-5)*3+10;
	return 0;
}