#include <cstdio>#include <cstring>#include <cmath>#include <string>#include <iostream>#include <algorithm>#include <queue>using namespace std;#define rep(i, n) for(int i=0; i<(n); ++i)#define for1(i,a,n) for(int i=(a);i<=(n);++i)#define for2(i,a,n) for(int i=(a);i<(n);++i)#define for3(i,a,n) for(int i=(a);i>=(n);--i)#define for4(i,a,n) for(int i=(a);i>(n);--i)#define CC(i,a) memset(i,a,sizeof(i))#define read(a) a=getint()#define print(a) printf("%d", a)#define dbg(x) cout << #x << " = " << x << endl#define printarr2(a, b, c) for1(i, 1, b) { for1(j, 1, c) cout << a[i][j]; cout << endl; }#define printarr1(a, b) for1(i, 1, b) cout << a[i]; cout << endlinline const int getint() { int r=0, k=1; char c=getchar(); for(; c<‘0‘||c>‘9‘; c=getchar()) if(c==‘-‘) k=-1; for(; c>=‘0‘&&c<=‘9‘; c=getchar()) r=r*10+c-‘0‘; return k*r; }inline const int max(const int &a, const int &b) { return a>b?a:b; }inline const int min(const int &a, const int &b) { return a<b?a:b; } const int N=20005;int p[N], n, m, ans;struct ED { int x, y, w; }e[N];bool cmp(const ED &a, const ED &b) { return a.w>b.w; }const int ifind(const int &x) { return x==p[x]?x:p[x]=ifind(p[x]); } int main() {	read(n); read(m);	for1(i, 1, m) read(e[i].x), read(e[i].y), read(e[i].w);	sort(e+1, e+1+m, cmp);	int tot=0;	for1(i, 1, n) p[i]=i;	for1(i, 1, m) {		int fx=ifind(e[i].x), fy=ifind(e[i].y);		if(fx!=fy) {			p[fx]=fy;			ans+=e[i].w;			++tot;		}	}	if(tot<n-1) puts("-1");	else print(ans);	return 0;}

Silver