import math
def meteor(n):
	r = .01
	m=21.
	x = 200.*1000.
	v = 0.
	H = 1.
	p = 1.2
	g = 9.8
	t_max = -x/v*10.
	dt = t_max/n
	for i in range(n):
		dx = v*dt
		x = x+dx
		if x<0.:
			return v
		F = 3.14/4*p*v**2*r**2
		a = F/m
		dv = a*dt
		v = v+dv
	return -999.
print(meteor(100000))