zoj 2256 Mincost

#include<stdio.h>
int main(void)
{
    int kil;
    int flag=0;
    double sum;
    while(scanf("%d",&kil)&&kil!=0)
    {
        sum=0;
        flag=0;
        while(kil)
        {
            if(kil<=4)
            {
                sum+=10;
                kil-=kil;
            }
            else if(kil<=8)
            {
                sum+=(kil-4)*2+10;
                kil-=kil;
            }
            else if(kil<=12)
            {
                flag=1;
                sum+=18+(kil-8)*2.4;
                kil-=kil;
            }
            else
            {
                sum+=18;
                kil-=8;
            }
        }
        printf(flag==0? "%.0lf\n":"%.1lf\n",sum);
    }
    return 0;
}