# 1932 정수 삼각형

n = int(input()) # 1<= n <= 500

data=[]
for i in range(n):
  data.append(list(map(int, input().split())))

for i in range(n-1):
  for j in range(len(data[i+1])):
    if ( j==0 ):
      data[i+1][j] += data[i][j]
    elif ( j == len(data[i+1])-1 ):
      data[i+1][j] += data[i][-1]
    else :
      data[i+1][j] += max( data[i][j-1] , data[i][j] )

print(max(data[n-1]))