#include <bits/stdc++.h>#define ll long long#define maxn 1010using namespace std;struct edge{    ll from,to,weight;};int cmp(edge a,edge b){    return a.weight<b.weight;}vector<edge>edges;int fa[maxn];int find(int x){    return x==fa[x]?x:(fa[x] = find(fa[x]));}void init(int n){    for(int i=1;i<=n;i++) fa[i] = i;}int main(){    ll n,m,i,j,a,b,c, ma = -1e17,mi = 1e17, ans = 1e18;    cin>>n>>m;    for(i=0;i<m;i++){        cin>>a>>b>>c;        edges.push_back((edge){a,b,c});    }    sort(edges.begin(), edges.end(), cmp);    for(i=0;i<m;i++){        init(n);        mi = 1e17;        ma = -1e18;        for(j=i;j<m;j++){            edge e = edges[j];            mi = min(e.weight, mi);            ma = max(e.weight, ma);            int fau = find(e.from);            int fav = find(e.to);            if(fau != fav) fa[fau] = fav;            if(find(n) == find(1)) break;        }        if(j<m) ans = min(ans, ma-mi);    }    cout<<ans<<endl;    return 0;}