#include<stdio.h>
int max(int a, int b)
{
    return (a > b ? a : b);
}
int main()
{
    int n;
    while (scanf("%d",&n) != EOF)
    {
        int data[100][100] = {0};
        int i, j;
        for (i = 0; i < n; i++)
            for (j = 0; j <= i; j++)
                scanf("%d",&data[i][j]);
        int dp[100][100] = {0};
        for (j = 0; j < n; j++)
            dp[n-1][j] = data[n-1][j];
        for (i = n - 1; i >= 0; i--)
        {
            for (j = 0; j < n; j++)
            {
                dp[i][j] = data[i][j] + max(dp[i+1][j], dp[i+1][j+1]);
            }
        }
        printf("%d\n",dp[0][0]);
    }
    return 0;
}