#include <bits/stdc++.h>
using namespace std;
#define fast ios ::sync_with_stdio(false), cin.tie(0), cout.tie(0)
#define endl '\n'
using ll = long long;
typedef pair<int, int> PII;
#define OUT(v)                         \
    for (int k = 0; k < v.size(); ++k) \
        cout << v[k] << ' ';           \
    cout << endl;
const int N = 1e5 + 10;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
ll mul(ll x, ll y) {return (1LL * x * y) % mod; }
int dx[] = {0, -1, 0, 1}, dy[] = {-1, 0, 1, 0};
int Dx[] = {0, -1, 0, 1, 1, -1, -1, 1}, Dy[] = {-1, 0, 1, 0, 1, -1, 1, -1};

int f[N];


int dp[N];



void solve() {
    int n;
    cin >> n;
    memset(dp, -inf, sizeof dp);
    dp[1] = 0;
    int mx = -inf;
    for (int i = 1; i <= n; i++) {
        for (int j = i; j >= 1; j--) {
            int x;
            cin >> x;
            dp[j] = max(dp[j], dp[j-1]) + x;
            if (i == n) mx = max(mx, dp[j]);
        }
    }

    cout << mx;
}

int main() {
    solve();
    return 0;
}