output_description: Print the letter that follows C in alphabetical order.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      C
attempt: n = int(input())
  x = [0] * n
  y = [0] * n
  for i in range(n):
      x[i], y[i] = map(int, input().split())
  if n == 2:
      print(((x[0] - x[1]) ** 2 + (y[0] - y[1]) ** 2) ** (1 / 2) / 2)
  else:
      ans = 10**5
      A = [0] * 3
      B = [0] * 3
      for i in range(n - 2):
          for j in range(i + 1, n - 1):
              A[0] = x[j] - x[i]
              A[1] = y[j] - y[i]
              A[2] = A[0] * (x[i] + x[j]) / 2 + A[1] * (y[i] + y[j]) / 2
              for k in range(j + 1, n):
                  B[0] = x[k] - x[i]
                  B[1] = y[k] - y[i]
                  B[2] = B[0] * (x[i] + x[k]) / 2 + B[1] * (y[i] + y[k]) / 2
                  if (
                      A[0] * B[1] == A[1] * B[0] and A[0] * B[1] != 0
                  ):  # 三点が同一直線状に存在1
                      r = (
                          (max(x[i], x[j], x[k]) - min(x[i], x[j], x[k])) ** 2
                          + (max(y[i], y[j], y[k]) - min(y[i], y[j], y[k])) ** 2
                      ) ** (1 / 2) / 2
                      xc = (max(x[i], x[j], x[k]) + min(x[i], x[j], x[k])) / 2
                      yc = (max(y[i], y[j], y[k]) + min(y[i], y[j], y[k])) / 2
                  elif A[0] == B[0] == 0:  # 2
                      r = (max(y[i], y[j], y[k]) - min(y[i], y[j], y[k])) / 2
                      xc = x[i]
                      yc = (max(y[i], y[j], y[k]) + min(y[i], y[j], y[k])) / 2
                  elif A[1] == B[1] == 0:  # 3
                      r = (max(x[i], x[j], x[k]) - min(x[i], x[j], x[k])) / 2
                      yc = y[i]
                      xc = (max(x[i], x[j], x[k]) + min(x[i], x[j], x[k])) / 2
                  else:
                      xc = (A[2] * B[1] - A[1] * B[2]) / (A[0] * B[1] - A[1] * B[0])
                      yc = (A[0] * B[2] - A[2] * B[0]) / (A[0] * B[1] - A[1] * B[0])
                      r = ((x[i] - xc) ** 2 + (y[i] - yc) ** 2) ** (1 / 2)
                  aa = 0
                  r = min(r * 1.000000999, r + 0.000000999)
                  for l in range(n):
                      if ((x[l] - xc) ** 2 + (y[l] - yc) ** 2) ** (1 / 2) > r:
                          aa = 1
                  if aa == 0:
                      if r < ans:
                          ans = r
      print(ans)
  
problem_description: Statement
  
  Given is a lowercase English letter C that is not `z`. Print the letter that
  follows C in alphabetical order.
samples: [{"input": "a", "output": "b\n    \n\n`a` is followed by `b`.\n\n* * *"}, {"input": "y", "output": "z\n    \n\n`y` is followed by `z`."}]