import math

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

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

print(distance)
import math

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

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

print(distance)
import math

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

import math

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

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