local ffi = require 'ffi'
local M = ffi.load 'gmp'

ffi.cdef [[
typedef unsigned long mp_bitcnt_t;
typedef unsigned long mp_limb_t;
typedef long mp_exp_t;
typedef struct {
	int _mp_prec;
	int _mp_size;
	mp_exp_t _mp_exp;
	mp_limb_t * _mp_d;
} __mpf_struct;
typedef __mpf_struct mpf_t[1];
typedef const __mpf_struct * mpf_srcptr;
typedef __mpf_struct * mpf_ptr;
void __gmpf_init_set_ui(mpf_ptr, unsigned long);
void __gmpf_div_ui(mpf_ptr, mpf_srcptr, unsigned long);
void __gmpf_mul_ui(mpf_ptr, mpf_srcptr, unsigned long);
void __gmpf_set_default_prec(mp_bitcnt_t);
int __gmp_printf(const char *, ...);
]]

M.__gmpf_set_default_prec(128ULL)
M.__gmp_printf("%.15Ff\n", (function (n, g, v)
	local t=ffi.new("mpf_t")
	M.__gmpf_init_set_ui(t,n/5ULL)
	M.__gmpf_mul_ui(t,t,g+0ULL)
	M.__gmpf_div_ui(t,t,v+0ULL)
	return t
end)(io.stdin:read("*n"), io.stdin:read("*n"), io.stdin:read("*n")))