from math import sqrt

x1, y1, x2, y2 = list(map(float, input().split()))

r = sqrt((x2 - x1)**2 + (y2 - y1)**2)

print(r)
import math

x1, y1, x2, y2 = list(map(float, input().split()))

print((math.sqrt((x2 - x1)**2 + (y2 -y1)**2)))



from math import sqrt

x1, y1, x2, y2 = list(map(float, input().split()))
r = sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)
print(r)

import math

x1, y1, x2, y2 = list(map(float, input().split()))
print((math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)))

-from math import sqrt +import math -r = sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) -print(r) +print((math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)))