4 5
1 2 1
1 3 4
2 3 2
2 4 5
3 4 3

6

import heapq
n,m=map(int,input().split())
g=[[] for _ in range(n+1)]
for _ in range(m):
    u,v,w=map(int,input().split())
    g[u].append((w,v)); g[v].append((w,u))
visited=[False]*(n+1)
hp=[(0,1)]; total=0
while hp:
    cost,node=heapq.heappop(hp)
    if visited[node]: continue
    visited[node]=True; total+=cost
    for w,nxt in g[node]:
        if not visited[nxt]: heapq.heappush(hp,(w,nxt))
print(total)