#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 110, INF = 0x3f3f3f3f, MOD = 1E9 + 7;
int n, a[N][N], f[N][N];

int main(int argc, char* argv[]) {
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= i; j++)
            cin >> a[i][j];

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= i; j++)
            f[i][j] = max(f[i - 1][j - 1], f[i - 1][j]) + a[i][j];

    int ans = -2e9;
    for (int i = 1; i <= n; i++)
        ans = max(ans, f[n][i]);
    cout << ans;
    return 0;
}