from atcoder.dsu import DSU

N, M = map(int, input().split())
edges = []
for _ in range(M):
    u, v, w = map(int, input().split())
    edges.append((w, u-1, v-1))
edges.sort(reverse=True, key=lambda x: x[0])

d = DSU(N)
res = 0
for w, u, v in edges:
    if not d.same(u, v):
        d.merge(u, v)
        res += w

print(2 * res)