triangle = []

f = open('018.txt', 'r')
for line in f:
	line.rstrip('\n')
	row_str = line.split(' ')
	row_int = [ int(x) for x in row_str ]
	triangle.append(row_int)
f.close()

for i in range(1, len(triangle)):
	rowlen = len(triangle[i])
	triangle[i][0] += triangle[i-1][0]
	triangle[i][rowlen-1] += triangle[i-1][rowlen-2]
	for j in range(1, rowlen-1):
		triangle[i][j] += max(triangle[i-1][j-1], triangle[i-1][j])

print max(triangle[-1])