AC answer

#include <bits/stdc++.h>

#define debug freopen("in.txt","r",stdin);freopen("out.txt","w",stdout)
#define N 105

using namespace std;

int n,maxv;
int a[N][N],dp[N][N];

void work()
{
cin>>n;
for(int i=1;i<=n;i++)
for(int j=1;j<=i;j++)
cin>>a[i][j];
for(int i=1;i<=n;i++)
for(int j=1;j<=i;j++)
{
dp[i][j]=max(dp[i-1][j],dp[i-1][j-1])+a[i][j];
if(i==n) maxv=max(maxv,dp[i][j]);
}
cout<<maxv;
}

int main()
{
//debug;
work();
return 0;
}