import math
r,x,y,x1,y1 = [int(x) for x in input().split(" ")]

val = abs(math.ceil(((x1-x) + (y1-y))/(r*math.sqrt(2))))
val1 = abs(math.ceil((x1-x)/r))
val2 = abs(math.ceil((y1 - y)/r))

if val % 2 == 0:
    val = ((val) // 2)
else:
    val = (((val) + 1) // 2)

if val1 % 2 == 0:
    val1 = (val1) // 2
else:
    val1 = ((val1 + 1) // 2)
    
if val2 % 2 == 0 :
    val2 = val2 // 2
else:
    val2 = (val2 + 1) // 2

print(max(val1,val2,val))