a = []

ff = open('triangle.txt', 'r')
for i in ff.readlines():
  tmp = i.split(' ')
  for j in xrange(len(tmp)):
    tmp[j] = int(tmp[j])
  a.append(tmp)
ff.close()


path = a[-1][:]
for i in xrange(len(a) - 2, 0, -1):
  newpath = []
  for j in xrange(i + 1):
    better = max(path[j], path[j + 1])
    newpath.append(a[i][j] + better)
  path = newpath
print max(path) + a[0][0]


'''
path = [[a[0][0], [a[0][0]]]]
for i in xrange(1, len(a)):
  newpath = []
  tmp = path[0][1][:]
  tmp.append(a[i][0])
  newpath.append([path[0][0] + a[i][0], tmp])
  for j in xrange(1, i):
    flag = (path[j - 1][0] > path[j][0]) and -1 or 0
    tmp = path[j + flag][1][:]
    tmp.append(a[i][j])
    newpath.append([path[j + flag][0] + a[i][j], tmp])
  tmp = path[i - 1][1][:]
  tmp.append(a[i][i])
  newpath.append([path[i - 1][0] + a[i][i], tmp])
  path = newpath

maxx = [0, 0]
for i in path:
  if i[0] > maxx[0]:
    maxx = i
print maxx
'''