#include<iostream>
#include<algorithm>
using namespace std;
const int N = 505;
int num[N][N],dp[N][N];
int main() {
    int n;
    cin >> n;
    for (int i = 1;i <= n;i++) {
        for (int j = 1;j <= i;j++) {
            cin >> num[i][j];
        }
    }
    for (int i = 0;i <= n;i++) {
        for (int j = 0;j <= i + 1;j++) {
            dp[i][j] = -1e9;
        }
    }
    dp[1][1] = num[1][1];
    for (int i = 2;i <= n;i++) {
        for (int j = 1;j <= i;j++) {
               dp[i][j] = max(dp[i - 1][j],dp[i - 1][j - 1]) + num[i][j]; 
        }
    }
    int ans = -100000;
    for (int i = 1;i <= n;i++) {
        ans = max(dp[n][i],ans);
    }
    cout << ans << endl;
}