#include <algorithm>
#include <cstdio>
#include <cstring>

using namespace std;

const int N = 100;

int dp[N], tri[N][N];
// dp[i] means the max sum from the ith col of curr row to the last row.

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++)
    for (int j = 0; j < i + 1; j++) scanf("%d", &tri[i][j]);
  memcpy(dp, tri[n - 1], n * sizeof(int));
  for (int i = n - 1; 0 < i; i--)
    for (int j = 0; j < i; j++) dp[j] = tri[i - 1][j] + max(dp[j], dp[j + 1]);
  printf("%d\n", dp[0]);
  return 0;
}