//9193332 ylwh 1163 Accepted 408K 32MS GCC 366B 2011-08-19 14:48:37
#include <stdio.h>
int s[5001];
int main()
{
int n, i, j, k, cnt;
while(scanf("%d", &n)!= EOF)
{
cnt = 0;
for(i=1; i<=n; i++)
for(j=1; j<=i; j++)
scanf("%d", &s[++cnt]);
for(i=n-1; i>=1; i--)
for(j=1, k=(i-1)*i/2; j<=i; j++)
s[j+k] += s[j+k+i] > s[j+i+k+1] ? s[j+k+i] : s[j+i+k+1];
printf("%d\n", s[1]);
}
return 0;
}