//2008.5.20 07:59:04 Accepted 2256 C++ 00:00.00 836K 天将降大任于我
//Mincost
// 纯数学方法，列出分段函数表达式即可得
#include<iostream>
using namespace std;
int main()
{
double n,s;
while(scanf("%lf",&n)&&n)
{ s=0;
if(n<=4) {printf("10\n");continue;}
else
{
int t=n/8;
s+=t*18;
n=n-t*8; //double k=n%8;
if(n<=4) s+=2.4*n;
else s+=10+(n-4)*2;
int k=s;
if(s-k<=0.000)
printf("%.0lf\n",s);
else printf("%.1lf\n",s);
}
}
return 0;
}
心难泰，世风坏，旧时正气今何在？正义寡，人情薄，闻道虽多，茅塞不开。怪！怪！怪！
空等待，几多载，冲出重围人心快！暴雨打，狂风袭，任他折磨，此志难改。耐！耐！耐！
