[백준] 1932번 정수 삼각형

n = int(input())
dp = []
for i in range(n):
    dp.append(list(map(int, input().split())))
    
for i in range(1,n):
    for j in range(len(dp[i])):
        if j == 0:
            dp[i][j]+=dp[i-1][j]
        elif j == len(dp[i])-1:
            dp[i][j]+=dp[i-1][j-1]
        else:
            dp[i][j]+=max(dp[i-1][j], dp[i-1][j-1])
            
print(max(dp[n-1]))