#include <stdio.h>
#include <stdlib.h>

#define min(X,Y) (((X) <= (Y)) ? (X) : (Y))
#define max(X,Y) (((X) >= (Y)) ? (X) : (Y))

int main()
{
    int N;
    scanf("%d", &N);
    long a[100][100];
    long long dp[100][100]; //best way to [i][j]
    for (int i = 0; i < 100; i++) {
        for (int j = 0; j < 100; j++) a[i][j] = 0;
    }
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < i + 1; j++) {
            scanf ("%ld", &a[i][j]);
        }
    }
    dp[0][0] = a[0][0];
    for (int i = 1; i < N; i++) {
        dp[i][0] = a[i][0] + dp[i-1][0];
        for (int j = 1; j < i; j++) {
            dp[i][j] = a[i][j] + max (dp[i-1][j-1], dp[i-1][j]);
        }
        dp[i][i] = a[i][i] + dp[i-1][i-1];
    }
    long M = 0;
    for(int j = 0; j < N; j++) {
        if (M < dp[N-1][j]) M = dp[N-1][j];
    }
    printf ("%ld", M);
    return 0;
}