https://www.acmicpc.net/problem/1932
import sys
n=int(sys.stdin.readline())
tri=[[0]]
for i in range(1, n+1):
tri.append([0]+list(map(int, sys.stdin.readline().split())))
dp=[[0]*(n+1) for _ in range(n+1)]
dp[1][1]=tri[1][1]
for i in range(2, n+1):
for j in range(1, len(tri[i])):
dp[i][j]=max(dp[i-1][j-1], dp[i-1][j])+tri[i][j]
print(max(dp[n]))