import sys

# Parse the command line.
if (len(sys.argv) != 2):
  print "USAGE: read-tree.py <tree>"
  sys.exit(1)
treeFilename = sys.argv[1]

############################################################################
# Split up a tree string into two subtree strings.  Assumes that the
# string starts and ends with parentheses.
def splitTreeString(treeString):

  # Remove the leading and trailing parentheses.
  treeString = treeString[1:-1]

  # Search for the middle comma.
  numParens = 0
  for index in range(0, len(treeString)):
    thisChar = treeString[index]
    if (thisChar == "("):
      numParens += 1
    elif (thisChar == ")"):
      numParens -= 1
    elif ((thisChar == ",") and (numParens == 0)):
      leftString = treeString[:index]
      rightString = treeString[index+1:]
      return((leftString, rightString))

  # If we reach here, then the string is misformatted.
  print "Can't parse string %s." % treeString

############################################################################
def readTree (treeString):

  # Remove leading and trailing whitespace.
  treeString = treeString.strip()
    
  # If the string doesn't start with a parenthesis, this is the base case.
  if (treeString[0] != "("):
    return(treeString)
  else:
    # If there is a leading parenthesis, split and recurse.
    (leftString, rightString) = splitTreeString(treeString)
    return([readTree(leftString), readTree(rightString)])
  
############################################################################
def countLeaves (myTree):
  if (isinstance(myTree, str)):
    return 1
  else:
    return(countLeaves(myTree[0]) + countLeaves(myTree[1]))

############################################################################
# MAIN PROCEDURE
############################################################################

# Get the tree as a string.
treeFile = open(treeFilename, "r")
treeString = treeFile.readline()
treeFile.close()

# Initialize an empty tree.
myTree = readTree(treeString)

# Count the leaves.
print "Read %d species from %s." % (countLeaves(myTree), treeFilename)