export {};

class PriorityQueue {
  private heap: [number, number][] = [];

  push(item: [number, number]): void {
    this.heap.push(item);
    this._bubbleUp();
  }

  pop(): [number, number] | undefined {
    if (this.heap.length === 0) return undefined;
    if (this.heap.length === 1) return this.heap.pop();
    const root = this.heap[0];
    this.heap[0] = this.heap.pop()!;
    this._bubbleDown();
    return root;
  }

  size(): number {
    return this.heap.length;
  }

  isEmpty(): boolean {
    return this.heap.length === 0;
  }

  private _bubbleUp(): void {
    let index = this.heap.length - 1;
    while (index > 0) {
      const parentIdx = Math.floor((index - 1) / 2);
      if (this.heap[index][0] >= this.heap[parentIdx][0]) break;
      [this.heap[index], this.heap[parentIdx]] = [this.heap[parentIdx], this.heap[index]];
      index = parentIdx;
    }
  }

  private _bubbleDown(): void {
    let index = 0;
    const length = this.heap.length;
    
    while (true) {
      let smallestIdx = index;
      const leftIdx = 2 * index + 1;
      const rightIdx = 2 * index + 2;

      if (leftIdx < length && this.heap[leftIdx][0] < this.heap[smallestIdx][0]) {
        smallestIdx = leftIdx;
      }
      
      if (rightIdx < length && this.heap[rightIdx][0] < this.heap[smallestIdx][0]) {
        smallestIdx = rightIdx;
      }

      if (smallestIdx === index) break;

      [this.heap[index], this.heap[smallestIdx]] = [this.heap[smallestIdx], this.heap[index]];
      index = smallestIdx;
    }
  }
}

const input = require("fs").readFileSync(0).toString().trim().split("\n");
const [V, E]: number[] = input[0].split(" ").map(Number);

let graph: number[][][] = Array.from({length: V+1}, () => []);
for(let i=1; i<=E; i++) {
    let [u,v,w]: number[] = input[i].split(" ").map(Number);
    graph[u].push([w,v]);
    graph[v].push([w,u]);
}

const prim = (): number => {
    let visited: boolean[] = new Array(V+1).fill(false);
    let pq = new PriorityQueue();
    pq.push([0,1]);

    let total_weight: number = 0;
    let count: number = 0;

    while(pq.size() !== 0) {
        let [w, v]: number[] = pq.pop();

        if(visited[v]) continue;

        visited[v] = true;
        total_weight += w;
        count++;

        if(count === V) break;

        for(let next of graph[v]) {
            let [nw, nv] = next;
            if(!visited[nv]) pq.push([nw, nv]);
        }
    }

    return total_weight;
}

console.log(prim());