#include <bits/stdc++.h>

using namespace std;

int a[101][101] = {0};
int f[101][101] = {0};

int main() {
    //输入+输出重定向
    freopen("../1272.txt", "r", stdin);
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= i; ++j) {
            cin >> a[i][j];
        }
    }
    //初始化最后一行的dp
    for (int i = 1; i <= n; ++i) {
        f[n][i] = a[n][i];
    }
    //从倒数第二行开始，反向建构
    for (int i = n - 1; i >= 1; i--) {
        for (int j = 1; j <= i; ++j) {
            f[i][j] = a[i][j] + max(f[i + 1][j], f[i + 1][j + 1]);
        }
    }
    cout << f[1][1] << endl;
    //关闭文件
    fclose(stdin);
    return 0;
}