class UnionFind():
  def __init__(self, n): self.data = [-1 for _ in range(n)]
  
  def find(self, x):
    stack = []
    while self.data[x] >= 0:
      stack.append(x)
      x = self.data[x]
    while len(stack):
      y = stack.pop()
      self.data[y] = x
    return x
  
  def unite(self, x, y):
    x, y = self.find(x), self.find(y)
    if x == y: return
    if self.data[x] > self.data[y]: x, y = y, x
    self.data[x] += self.data[y]
    self.data[y] = x
    return
  
  def same(self, x, y): return self.find(x) == self.find(y)
  
  def size(self, x): return -self.data[self.find(x)]

N, M = map(int, input().split())
E = []
for _ in range(M):
  a, b, c = map(int, input().split())
  E.append((c, a - 1, b - 1))
E.sort()
ans = 0
uf = UnionFind(N)
while len(E):
  c, a, b = E.pop()
  if uf.same(a, b):
    continue
  uf.unite(a, b)
  ans += c
print(ans * 2)