import sys

MIN_NUMBER = -sys.maxsize-1

def isPrime(num):
  if num == 0 or num == 1 or num < 0:
    return False
  for i in range(2,int(num**0.5)+1):
    if num % i == 0:
      return False
  return True

def readFile(filename):
  f = open(filename, "r")
  arr = []
  lines = f.readlines()
  for line in lines:
    arr.append(line.strip().split(" "))
  f.close()
  return arr

def typecast(arr):
  for i in range(len(arr)):
    for j in range(len(arr[i])):
      arr[i][j] = int(arr[i][j])
  return arr

def extractPrimes(arr):
  for i in range(len(arr)):
    for j in range(len(arr[i])):
      if isPrime(arr[i][j]):
        arr[i][j] = MIN_NUMBER
  return arr

def maxSum(arr):
  while len(arr) > 1:
    tmp = []
    for i in range(len(arr[-2])):
      val = arr[-2][i]
      left, right = arr[-1][i], arr[-1][i+1]

      if val == MIN_NUMBER:
        tmp.append(MIN_NUMBER)
        continue
      elif left == MIN_NUMBER and right == MIN_NUMBER:
        tmp.append(MIN_NUMBER)
      else:
        tmp.append(max(left+val, right+val))
       
    del arr[-2:]
    arr.append(tmp)
  return arr[0][0]

arr = readFile("file.txt")
arr = typecast(arr)
arr = extractPrimes(arr)
print(f'Max sum : {maxSum(arr)}')