#include <iostream>

 #include <cstdio>

 #include <cmath>

 #include <vector>

 #include <cstring>

 #include <string>

 #include <algorithm>

 #include <string>

 #include <set>

 #include <functional>

 #include <numeric>

 #include <sstream>

 #include <stack>

 #include <map>

 #include <queue>

 #pragma comment(linker, "/STACK:102400000,102400000")

 #define CL(arr, val)    memset(arr, val, sizeof(arr))

 #define ll long long

 #define inf 0x7f7f7f7f

 #define lc l,m,rt<<1

 #define rc m + 1,r,rt<<1|1

 #define pi acos(-1.0)

 #define L(x)    (x) << 1

 #define R(x)    (x) << 1 | 1

 #define MID(l, r)   (l + r) >> 1

 #define Min(x, y)   (x) < (y) ? (x) : (y)

 #define Max(x, y)   (x) < (y) ? (y) : (x)

 #define E(x)        (1 << (x))

 #define iabs(x)     (x) < 0 ? -(x) : (x)

 #define OUT(x)  printf("%I64d\n", x)

 #define lowbit(x)   (x)&(-x)

 #define Read()  freopen("a.txt", "r", stdin)

 #define Write() freopen("b.txt", "w", stdout);

 #define maxn 1000000000

 #define N 500

 using namespace std;

 int dp[N][N];

 int main()

 {

     int n;

     scanf("%d",&n);

     for(int i=;i<n;i++)

         for(int j=;j<=i;j++) scanf("%d",&dp[i][j]);

     for(int i=n-;i>=;i--)

         for(int j=;j<=i;j++)

         dp[i][j]=dp[i][j]+max(dp[i+][j],dp[i+][j+]);

     printf("%d\n",dp[][]);

     return ;

 }

 #include <iostream>

 #include <cstdio>

 #include <cmath>

 #include <vector>

 #include <cstring>

 #include <string>

 #include <algorithm>

 #include <string>

 #include <set>

 #include <functional>

 #include <numeric>

 #include <sstream>

 #include <stack>

 #include <map>

 #include <queue>

 #pragma comment(linker, "/STACK:102400000,102400000")

 #define CL(arr, val)    memset(arr, val, sizeof(arr))

 #define ll long long

 #define inf 0x7f7f7f7f

 #define lc l,m,rt<<1

 #define rc m + 1,r,rt<<1|1

 #define pi acos(-1.0)

 #define L(x)    (x) << 1

 #define R(x)    (x) << 1 | 1

 #define MID(l, r)   (l + r) >> 1

 #define Min(x, y)   (x) < (y) ? (x) : (y)

 #define Max(x, y)   (x) < (y) ? (y) : (x)

 #define E(x)        (1 << (x))

 #define iabs(x)     (x) < 0 ? -(x) : (x)

 #define OUT(x)  printf("%I64d\n", x)

 #define lowbit(x)   (x)&(-x)

 #define Read()  freopen("a.txt", "r", stdin)

 #define Write() freopen("b.txt", "w", stdout);

 #define maxn 1000000000

 #define N 500

 using namespace std;

 int dp[N];

 int main()

 {

     //Read();

     int n,a,r=;

     scanf("%d",&n);

     for(int i=;i<=n;i++)

     {

         for(int j=i;j>=;j--)

         {

             scanf("%d",&a);

             dp[j]=max(dp[j],dp[j-])+a;

             r=max(r,dp[j]);

             //printf("%d ",dp[j]);

         }

        //printf("\n");

     }

     printf("%d\n",r);

     return ;

 }