#! /usr/bin/env python

#

# This file is a part of LEMON, a generic C++ optimization library.

#

# Copyright (C) 2003-2009

# Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

# (Egervary Research Group on Combinatorial Optimization, EGRES).

#

# Permission to use, modify and distribute this software is granted

# provided that this copyright notice appears in all copies. For

# precise terms see the accompanying LICENSE file.

#

# This software is provided "AS IS" with no warranty of any kind,

# express or implied, and with no claim as to its suitability for any

# purpose.

import sys

from mercurial import ui, hg

from mercurial import util

util.rcpath = lambda : []

if len(sys.argv)>1 and sys.argv[1] in ["-h","--help"]:

    print """

This utility just prints the length of the longest path

in the revision graph from revison 0 to the current one.

"""

    exit(0)

u = ui.ui()

r = hg.repository(u, ".")

N = r.changectx(".").rev()

lengths=[0]*(N+1)

for i in range(N+1):

    p=r.changectx(i).parents()

    if p[0]:

        p0=lengths[p[0].rev()]

    else:

        p0=-1

    if len(p)>1 and p[1]:

        p1=lengths[p[1].rev()]

    else:

        p1=-1

    lengths[i]=max(p0,p1)+1

print lengths[N]