MST

#include <iostream>
#include <stdio.h>
#include <vector>
#include <string>
#include <cmath>
#include <cstring>
#include <algorithm>


using namespace std;

int findd(int x, int parent[]){
    if(x == parent[x]) return x;
    return parent[x] = findd(parent[x], parent);
}

void join(int x, int y, int parent[], int sizee[]){
    int fx = findd(x, parent), fy = findd(y, parent);
    if(fx == fy)return;

    if(sizee[fx] > sizee[fy]){
        join(y, x, parent, sizee);
        return;
    }

    sizee[fy] += sizee[fx];
    parent[fx] = fy;
}

int main(){
    int M, N, x, y, z, parent[M], sizee[M], i = 0;

    cin >> M >> N;

    while(M != 0 || N != 0){
        for(int i = 0; i < M; i++){
            parent[i] = i;
            sizee[i] = 1;
        }

        vector<pair<int, pair<int, int> > > edges;

        for(int j = 0; j < N; ++j){
            cin >> x >> y >> z;
            edges.push_back(make_pair(z, make_pair(x, y)));
        }

        sort(edges.begin(), edges.end());

        int sum = 0;

        for(int i = 0; i < M; ++i){
            int a = edges[i].second.first;
            int b = edges[i].second.second;
            int w = edges[i].first;
            int fa = findd(a, parent);
            int fb = findd(b, parent);

            if(fa == fb) continue;

            join(a, b, parent, sizee);
            sum += w;
        }

        cout << sum << endl;
        cin >> M >> N;
    }


    return 0;
}