Please, try EDU on Codeforces! New educational section with videos, subtitles, texts, and problems. ×

F. Tree Destruction
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

You are given an unweighted tree with n vertices. Then n - 1 following operations are applied to the tree. A single operation consists of the following steps:

1. choose two leaves;
2. add the length of the simple path between them to the answer;
3. remove one of the chosen leaves from the tree.

Initial answer (before applying operations) is 0. Obviously after n - 1 such operations the tree will consist of a single vertex.

Calculate the maximal possible answer you can achieve, and construct a sequence of operations that allows you to achieve this answer!

Input

The first line contains one integer number n (2 ≤ n ≤ 2·105) — the number of vertices in the tree.

Next n - 1 lines describe the edges of the tree in form a i, b i (1 ≤ a i, b i ≤ n, a i ≠ b i). It is guaranteed that given graph is a tree.

Output

In the first line print one integer number — maximal possible answer.

In the next n - 1 lines print the operations in order of their applying in format a i, b i, c i, where a i, b i — pair of the leaves that are chosen in the current operation (1 ≤ a i, b i ≤ n), c i (1 ≤ c i ≤ n, c i = a i or c i = b i) — choosen leaf that is removed from the tree in the current operation.

See the examples for better understanding.

Examples
Input
31 21 3
Output
32 3 32 1 1
Input
51 21 32 42 5
Output
93 5 54 3 34 1 14 2 2