local ffi = require 'ffi'
local C = ffi.C

ffi.cdef [[
int printf(const char *, ...);
]]

C.printf("%ld.%s\n", (function (f, n, g, v)
	local a,b=n/5LL*g,v+0LL
	return a/b, f(a%b,b,15)
end)(function (a, b, l)
	local q,f="",tostring
	while #q<l do a=a*10LL q,a=q..f(a/b):sub(1,-3),a%b end
	return q
end, io.stdin:read("*n"), io.stdin:read("*n"), io.stdin:read("*n")))