用DP递推

/*
int      %o/%lo 8 %d/%i/%ld/%li 10 %x/%lx 16
longlong %lld
float    %f/%e
double   %lf/%le
char     %c
char[]   %s
'a'=97
'z'=122
'A'=65
'Z'=90
'0'=48
'9'=57
*/
#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <ctime>
#include <limits>
#include <assert.h>
#include <stdlib.h>
#pragma GCC optimize(3) //O3
//#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);//IOS
using namespace std;
#define LL long long
#define ull unsigned long long
const int N=10+10;
const int INF=0x3f3f3f3f;
const double pi=3.1416;
int n;
int a[N][N],f[N][N],ans;
int main(){
	//IOS;
	cin>>n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=i;j++){
			cin>>a[i][j];
			f[i][j]=max(f[i-1][j-1],f[i-1][j])+a[i][j];
		}
	}
	for(int i=1;i<=n;i++){
		ans=max(f[n][i],ans);
	}
	cout<<ans<<endl;
return 0;
}