#include <iostream>
using namespace std;
const int N = 550;
int a[N][N], f[N][N];
int main () {
int n;
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 ++) f[n][i] = a[n][i];
for (int i = n - 1; i >= 1; i --) {
for (int j = 1; j <= i; j ++) {
f[i][j] = max(f[i + 1][j], f[i + 1][j + 1]) + a[i][j];
}
}
cout << f[1][1];
return 0;
}