# -*- coding: utf-8 -*-
"""
Created on Thu May 14 23:02:21 2020

@author: Tom
"""
sequence = """
75
95 64
17 47 82
18 35 87 10
20 04 82 47 65
19 01 23 75 03 34
88 02 77 73 07 63 67
99 65 04 28 06 16 70 92
41 41 26 56 83 40 80 70 33
41 48 72 33 47 32 37 16 94 29
53 71 44 65 25 43 91 52 97 51 14
70 11 33 28 77 73 17 78 39 68 17 57
91 71 52 38 17 14 91 43 58 50 27 29 48
63 66 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
"""

num_sequence = [int(i) for i in sequence.split()]

# num_sequence = [3, 7, 4, 2, 4, 6, 8, 5, 9, 3]

num_rows = int((-1 + (1 + 8 * len(num_sequence)) ** 0.5) / 2)

print(num_rows)

for i in range(1, num_rows):
    for j in range(0, i + 1):
        if j == 0:
            num_sequence[i * (i + 1) // 2 + j] += \
                num_sequence[(i - 1) * i // 2]
        elif j == i:
            num_sequence[i * (i + 1) // 2 + j] += \
                num_sequence[(i + 1) * i // 2 - 1]
        else:
            num_sequence[i * (i + 1) // 2 + j] += \
                max(num_sequence[(i - 1) * i // 2 + j],
                    num_sequence[(i - 1) * i // 2 + j - 1])
print(max(num_sequence))
