Kruskal

#include<bits/stdc++.h>
#define M 2147483647
using namespace std;
struct node
{
	int u,v,w;
}a[200001];
int f[5001],n,m,ans,sum;
bool b[5001];
inline int findfather(int x)
{
	if(f[x]==x) return x;
	return f[x]=findfather(f[x]);
}
inline bool cmp(node x,node y)
{
	return x.w<y.w;
}
void kruskal()
{
	sort(a+1,a+m+1,cmp);
	for(register int i=1;i<=m;++i)
	{
		int fu=findfather(a[i].u),fv=findfather(a[i].v);
		if(fu==fv) continue;
		ans+=a[i].w,f[fu]=fv;
		if(++sum==n-1) break;
	}
}
int main()
{
	cin>>n>>m;
	for(register int i=1;i<=n;++i) f[i]=i;
	for(register int i=1;i<=m;++i)
	cin>>a[i].u>>a[i].v>>a[i].w;
	kruskal();
	if(sum==n-1) cout<<ans;
	else cout<<"None";
	return 0;
}