#include <bits/stdc++.h>
using namespace std;
const int N = 510;
const int INF = 0x3f3f3f3f;
int n;
int f[N];
int a[N][N];

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= i; j++)
            cin >> a[i][j];
    // 预求最大，先设最小
    memset(f, -0x3f, sizeof f);
    f[1] = a[1][1]; // 递推的初始化边界
    for (int i = 2; i <= n; i++)
        for (int j = i; j >= 1; j--)
            f[j] = max(f[j - 1], f[j]) + a[i][j];

    int res = -INF;
    for (int i = 1; i <= n; i++) res = max(res, f[i]);
    printf("%d", res);
    return 0;
}