import sys
sys.setrecursionlimit(10**6)

V, E = map(int, input().split())

edges = []
for _ in range(E) :
    u, v, w = map(int, input().split())
    edges.append((w,u,v))
    
edges.sort()

parent = [i for i in range(V+1)]
total_weight = 0

def find_parent(x) :
    if x != parent[x] :
        parent[x] = find_parent(parent[x])
    return parent[x]

def union_parent(x, y) :
    parentX = find_parent(x)
    parentY = find_parent(y)
    
    if parentX < parentY :
        parent[parentY] = parentX
    else :
        parent[parentX] = parentY

for w, u, v in edges :
    if find_parent(u) != find_parent(v) :
        total_weight += w
        union_parent(u, v)

print(total_weight)