#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <unordered_map>
#include "optimization.h"
#include <map>

#define all(a) a.begin, a.end()
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<vector<int>> table(n+1, vector<int>(n+1, 0));
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= i; j++){
            cin >> table[i][j];
        }
    }
    vector<vector<int>> dp(n+1, vector<int>(n+1, 0));
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= i; j++){
            dp[i][j] = max(dp[i-1][j], dp[i-1][j-1]) + table[i][j];
        }
    }
    int res = 0;
    for (int i = 0;i <= n; i++){
        res = max(res, dp[n][i]);
    }
    cout << res;
}