n,m=map(int,input().split())
abc=[[*map(int,input().split())]for _ in range(m)]
abc.sort(key=lambda x:-x[2])
uf=[*range(n)]
def find(x):
 q=[]
 while uf[x]^x:q+=x,;x=uf[x]
 for p in q:uf[p]=x
 return x
def unite(x,y):
 x,y=find(x),find(y)
 if x^y:uf[x]=y
s=0
for a,b,c in abc:
  a-=1;b-=1
  if find(a)!=find(b):
    unite(a,b)
    s+=c
print(s*2)