#include <stdio.h>#include <string.h>#include <stdlib.h>using namespace std;int n, m, fa[1010], ans;int find(int x){ int temp = x; while(fa[x] != x) { x = fa[x]; } fa[temp] = x; return x;}struct Edge{ int len, u, v;}edge[20010];int cmp(const void *a, const void *b){ return (*(Edge *)b).len - (*(Edge *)a).len;}int Kruskal(){ int num = 0, canfind = 0;; ans = 0; for(int i = 0; i < n; i++) fa[i] = i; qsort(edge, m, sizeof(edge[0]), cmp); for(int i = 0; i < m; i++) { int x = find(edge[i].u), y = find(edge[i].v); if(x != y) { ans += edge[i].len; num++; fa[x] = y; if(num == n - 1) {canfind = 1; break;} } } return canfind;}int main(){ int s, e, c; while(scanf("%d%d", &n, &m) != EOF) { for(int i = 0; i < m; i++) { scanf("%d%d%d", &s, &e, &c); edge[i].len = c; edge[i].u = s; edge[i].v = e; } if(Kruskal()) { printf("%dn", ans); } else printf("-1n"); } return 0;}
