What's wrong with my function?
long double f(int x)
{
 if (x>1)
 {
   long double t;
   if (((k-1)*v+15)>((n-x)*u))
     t=(k-1)*v+15;
   else
     t=(n-x)*u;
   return t+(x-1)*v+5+(x-1)*v;
 }
 else
 {
   return (n-1)*u;
 }
}
People give me some tests.

Edited by author 10.04.2008 19:46

Your source is right. But please don't remember that "If there are several equivalent variants, output such one in which Petr will go by foot the smaller distance."