https://www.acmicpc.net/problem/1626시간 2초, 메모리 128MBinput :V E(1 ≤ V ≤ 50,000, 1 ≤ E ≤ 200,000)u v w(0 <= w < 100,000)output : 두 번째로 작은 스패닝
https://www.acmicpc.net/problem/15481시간 2초, 메모리 512MBinput :N M (2 ≤ N ≤ 200,000, N-1 ≤ M ≤ 200,000)u v w (1 ≤ u, v ≤ n, u ≠ v, 1 ≤ w ≤ 10^9) out