print((function (f, g)
	return tostring(f(g(),g(),g())):sub(1,-3)
end)(function (a, b, c)
	if a<=c then
		local d=a+b-1
		return tostring(c/d*a+(c%d<a and c%d or a)):sub(1,-3)
	end
	return c
end, (function (M)
	M.cdef 'int scanf(const char *, ...);'
	local C,c = M.C,M.new("long[1]")
	return function () C.scanf("%ld",c) return c[0] end
end)(require'ffi')))