/*
ID: yuhung91
TASK: numtri
LANG: C++
*/
#pragma GCC optimzize("Ofast,no-stack-protector")
#include<bits/stdc++.h>
#define int long long
#define quick ios::sync_with_stdio(0);cin.tie(0);
#define rep(x,a,b) for(int x=a;x<=b;x++)
#define repd(x,a,b) for(int x=a;x>=b;x--)
#define lowbit(x) (x&-x)
#define sz(x) (int)(x.size())
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define mp make_pair
#define eb emplace_back
using namespace std;
typedef pair<int,int> pii;
void debug(){
    cout<<"\n";
}
template <class T,class ... U >
void debug(T a, U ... b){
    cout<<a<<" ",debug(b...);
}
const int N=1e3+7;
int x[N][N];
int dp[N][N];
const int INF=1e18;
signed main(){
    quick
    ifstream cin("numtri.in");ofstream cout("numtri.out");
    int n;
    cin>>n;
    rep(i,1,n){
        rep(j,1,i) cin>>x[i][j];
    }
    rep(i,1,n){
        rep(j,1,i){
            dp[i][j]=max(dp[i-1][j],dp[i-1][j-1])+x[i][j];
        }
    }
    int ans=0;
    rep(i,1,n){
        ans=max(ans,dp[n][i]);
    }
    cout<<ans<<"\n";
    return 0;
}