#include <stdio.h>

int main(void)
{
	long n;
	long g;
	long v;
	long k;
	long y;
	scanf("%ld%ld%ld",&n,&g,&v);
	k=n/5;
	y=g*k;
	printf("%f\n",(double)y/v);
	
	return 0;
}