output_description: Print the distance in real number. The output should not contain an absolute
  error greater than 10-4.
input_description: Four real numbers x1, y1, x2 and y2 are given in a line.
attempt: x, y, x_, y_ = map(float, input().split())
  X = abs(x - x_) ** 2
  Y = abs(y - y_) ** 2
  print("{:.4f}".format((X + Y) ** (1 / 2)))
  
problem_description: Distance
  
    
  
  Write a program which calculates the distance between two points P1(x1, y1)
  and P2(x2, y2).
samples: [{"input": "0 1 1", "output": ".41421356"}]