#include <stdio.h>

int main(void)
{
	int n;
	int g;
	int v;
	int k;
	int y;
	scanf("%d%d%d",&n,&g,&v);
	k=n/5;
	y=g*k;
	printf("%0.12f\n",(double)y/v);
	
	return 0;
}