n,m=map(int,input().split())
e=[]
for _ in range(m):
  a,b,c=map(int,input().split())
  a-=1
  b-=1
  e+=[(c,a,b)]
e.sort()

r=list(range(n))

def union(x,y):
  rx=root(x)
  ry=root(y)
  if rx==ry:
    return
  if rx>ry:
    rx,ry=ry,rx
  r[ry]=rx
  return

def root(x):
  p=x
  l=[p]
  while r[p]!=p:
    p=r[p]
    l+=[p]
  for p in l:
    r[p]=l[-1]
  return r[x]

ans=0
for c,a,b in e[::-1]:
  if root(a)!=root(b):
    union(a,b)
    ans+=c
print(ans*2)