public static void main(String[] args) throws IOException {

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

int n = Integer.parseInt(reader.readLine());

List<Integer>[] tryangle = new List[n];

for (int i = 0; i < n; i++) {

tryangle[i] = Arrays.stream(toIntArray(reader.readLine()))

.boxed()

.collect(Collectors.toList());

}

int[][] memo = new int[n][n]; //memoization

int maxSum = computeMaxSum(tryangle, 0, 0, memo);

System.out.println(maxSum);

}

private static int computeMaxSum(List<Integer>[] tryangle, int layer, int order, int[][] memo) {

if (memo[layer][order] > 0) {

return memo[layer][order];

}

int nowPoint = tryangle[layer].get(order);

if (layer == tryangle.length - 1) { //가장 최하단 layer

return nowPoint;

}

return memo[layer][order] = nowPoint + Math.max(computeMaxSum(tryangle, layer + 1, order, memo)

, computeMaxSum(tryangle, layer + 1, order + 1, memo));

}

private static void printTryangle(List<Integer>[] tryangle) {

for (int i = 0; i < tryangle.length; i++) {

tryangle[i].forEach(System.out::print);

System.out.println();

}

}

private static int[] toIntArray(String readLine) {

String[] strings = readLine.split(" ");

int[] result = new int[strings.length];

for (int i = 0; i < result.length; i++) {

result[i] = Integer.parseInt(strings[i]);

}

return result;

}