#include <bits/stdc++.h>
using namespace std;
int main(){
int n;
cin>>n;
int a[n+1][n+1],dp[n] = {};
for(int i = 1;i <= n;i++){
for(int j = 0;j < i;j++){
cin>>a[i][j];
}
}
for(int i = 0;i < n;i++){
dp[i] = a[n][i];
}
for(int i = n-1;i >= 1;i--){
for(int j = 0;j < i;j++){
dp[j] = max(dp[j],dp[j+1]) + a[i][j];
}
}
cout<<dp[0]<<endl;
return 0;
}
