from collections import deque

def treeFlow(n, tree):
    # Write your code here
    graph = [[] for _ in range(500010)]
    for a, b, w in tree:
        graph[a].append((b,w))
        graph[b].append((a,w))

    def bfs(start, dis):
        ans = 0
        qu = deque()
        qu.append((-1, start, 0))
        while qu:
            bef, cur, dis = qu.popleft()
            for nex_node, weight in graph[cur]:
                if nex_node == bef:
                    continue
                x = dis+weight
                qu.append((cur, nex_node, x))
                ans += x
        return ans
        
    answer = min(bfs(1, 0), bfs(n, 0))
    return answer