#include <algorithm>
#include <stdio.h>
using namespace std;
int dp[355][355];
int main(){
	int n;
	scanf("%d", &n);
	for(int i = 0; i < n; i++)
		for(int j = 0; j < i + 1; j++){
			scanf("%d", &dp[i][j]);
			if(i > 0){
				if(j - 1 >= 0)
					dp[i][j] = dp[i][j] + max(dp[i-1][j], dp[i - 1][j - 1]);
				else
					dp[i][j] = dp[i][j] + dp[i - 1][j];
			}
		}
	printf("%d\n", *(max_element(dp[n - 1], dp[n - 1] + n)));
	return 0;
}