#include<queue>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int n,m;
int tot=0;
int pa[5005];
int minn,maxx;
void re_0(){
	minn=1e9;
	maxx=-1e9;
	for(int i=1;i<=n;i++)
	 pa[i]=i;
}
struct data{
	int x,y,w;
}e[10005];
bool cmp1(data a,data b)
{
	return a.w<b.w;
}
bool cmp2(data a,data b)
{
	return a.w>b.w;
}
int find(int x)
{
	if(pa[x]==x) return x;
	return pa[x]=find(pa[x]);
}
void merge(int x,int y)
{
	int t1=find(x);
	int t2=find(y);
	pa[t1]=t2;
}
int main(){
freopen("dvalue.in","r",stdin);
freopen("dvalue.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++)
	{
		int x,y,w;
		scanf("%d%d%d",&x,&y,&w);
		e[++tot]=(data){x,y,w};
	}
	
	int ans=1e9;
	sort(e+1,e+1+tot,cmp1);
	for(int k=1;k<=tot;k++)
	{
		re_0();
		int cnt=0;
		int i;
		for(i=k;i<=tot;i++)
		{
			int x=e[i].x,y=e[i].y;
			int t1=find(x);
			int t2=find(y);
			if(t1==t2) continue;
			merge(t1,t2);
			minn=min(minn,e[i].w);
			maxx=max(maxx,e[i].w);
			cnt++;
		//	printf("%d %d %d\n",x,y,e[i].w);
			if(cnt==n-1) break;	
		}
		if(cnt==n-1)
			ans=min(maxx-minn,ans);
		else break;
	}
	

	printf("%d\n",ans);
	return 0;
}