#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
int main(void)
{
    double okane,goen,gas,roomtaiseki;
    scanf("%lf %lf %lf",&okane,&gas,&roomtaiseki);
    goen=floor(okane/5);
    gas*=goen;
    double noudo = (double)(gas/roomtaiseki);
    printf("%.11lf",noudo);
}