python
n = int(input())
num = [[int(i) fori in input().split()] for_ in range(n)]
result = []
result = num[0][0]
fori in range(1,n):
forj in range(i+1):
ifj==0:
num[i][j] = num[i][j]+num[i-1][j]
elif j==i:
num[i][j] = num[i][j]+num[i-1][j-1]
else:
num[i][j] = num[i][j]+ max(num[i-1][j],num[i-1][j-1])
result = max(result,num[i][j])
print(result)