/*
欧拉计划第18题, DP,滑雪
answer: 1074
*/
#include<bits/stdc++.h>
using namespace std;
const int N = 1000;
int d[N][N];
int ans[N][N], n;
int main(void)
{
for (int i = 1; i <= 15; ++ i)
for (int j = 1; j <= i; ++ j)
{
cin >> d[i][j];
ans[i][j] = max(ans[i-1][j-1], ans[i-1][j]) + d[i][j];
}
int v = 0;
for (int i = 1; i <= 15; ++ i) v = max(v, ans[15][i]);
cout << v << endl;
return 0;
}