import sys

data = sys.stdin.read().split()
n = int(data[0])
m = int(data[1])
edges = []
idx = 2
for _ in range(m):
    edges.append((int(data[idx+2]), int(data[idx]), int(data[idx+1])))
    idx += 3
edges.sort()
p = list(range(n + 1))
def find(i):
    r = i
    while r != p[r]:
        r = p[r]
    c = i
    while c != r:
        p[c], c = r, p[c]
    return r
ans = 0
cnt = 0
for w, u, v in edges:
    ru = find(u)
    rv = find(v)
    if ru != rv:
        p[ru] = rv
        ans += w
        cnt += 1
        if cnt == n - 1:
            break
print(ans)