#include <stdio.h>

int main(void)
{
     long hand, gus, v;
     double five;

     scanf("%ld %ld %ld", &hand, &gus, &v);

     five = hand / 5;
     gus = gus * five;
     printf("%.20lf\n", (double)gus / v);

     return 0;
}