https://www.acwing.com/problem/content/900/
#include<bits/stdc++.h>
using namespace std;
const int N=510;
int f[N][N],n;
int main(void)
{
cin>>n;
memset(f,-0x3f,sizeof f);
for(int i=1;i<=n;i++)
for(int j=1;j<=i;j++)
cin>>f[i][j];
for(int i=n-1;i>=1;i--)
for(int j=1;j<=i;j++) f[i][j]=max(f[i+1][j],f[i+1][j+1])+f[i][j];
cout<<f[1][1];
return 0;
}