if let input1 = readLine(),
   let nums1 = input1.split(separator: " ").compactMap({Int($0)}) as? [Int],
   let V = nums1.first, let E = nums1.last
{
    var edges: [(u: Int, v: Int, w: Int)] = []
    for _ in 1...E {
        guard let input2 = readLine(),
              let nums2 = input2.split(separator: " ").compactMap({Int($0)}) as? [Int],
              nums2.count == 3
        else { break }
        
        let (u, v, w) = (nums2[0], nums2[1], nums2[2])
        edges.append((u: u, v: v, w: w))
    }
    
    edges.sort{$0.w < $1.w}
    
    var parents:[Int] = Array(0...V)
    
    func find(_ x: Int) -> Int {
        if x != parents[x] {
            parents[x] = find(parents[x])
        }
        return parents[x]
    }
    
    func union(_ x: Int, _ y: Int) {
        let a = find(x)
        let b = find(y)
        
        if a > b {
            parents[a] = b
        }
        else {
            parents[b] = a
        }
    }
    
    var total_weight = 0
    for (u, v, w) in edges {
        if find(u) != find(v) {
            total_weight += w
            union(u, v)
        }
    }
    
    print(total_weight)
}