3457. Cow Pinball

import java.io.*;

public class Main {

    /**
     * http://acm.tju.edu.cn/toj/showp3457.html
     * @author hunglee
     */
    public static void main(String[] args) throws IOException {
        
        StreamTokenizer in = new StreamTokenizer(new BufferedReader(
                new InputStreamReader(System.in)));
        PrintWriter out = new PrintWriter(System.out);
        
        int r, a[][];
        in.nextToken();
        r = (int) in.nval;
        a = new int[r][];
        for (int i = 0; i < r; ++i) {
            a[i] = new int[i + 1];
            for (int j = 0; j <= i; ++j) {
                in.nextToken();
                a[i][j] = (int) in.nval;
            }
        }
        for (int i = 1; i < r; ++i) {
            a[i][0] += a[i - 1][0];
            a[i][i] += a[i - 1][i - 1];
            for (int j = 1; j < i; ++j)
                a[i][j] += Math.max(a[i - 1][j - 1], a[i - 1][j]);
        }
        int res = -1;
        for (int j = 0; j < r; ++j)
            if (res < a[r - 1][j])
                res = a[r - 1][j];
        out.println(res);
        out.flush();
    }

}