// luogu-judger-enable-o2
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
#define N 400050
#define M 200050
#define ls ch[p][0]
#define rs ch[p][1]
#define get(x) (ch[f[x]][1]==x)
struct A {int x,y,v;
}a[N];
bool cmp(const A &x,const A &y){return x.v>y.v;}
int ch[N][2],f[N],val[N],siz[N],rev[N],mx[N],tot,n,m,kill[M];
inline bool isrt(int p) {return ch[f[p]][1]!=p&&ch[f[p]][0]!=p;
}
inline void pushup(int p) {mx[p]=p;if(val[mx[ls]]>val[mx[p]]) mx[p]=mx[ls];if(val[mx[rs]]>val[mx[p]]) mx[p]=mx[rs];
}
inline void pushdown(int p) {if(rev[p]) {swap(ch[ls][0],ch[ls][1]);swap(ch[rs][0],ch[rs][1]);rev[ls]^=1; rev[rs]^=1;rev[p]=0;}
}
void update(int p) {if(!isrt(p))  update(f[p]);pushdown(p);
}
void rotate(int x) {int y=f[x],z=f[y],k=get(x);if(!isrt(y)) ch[z][ch[z][1]==y]=x;ch[y][k]=ch[x][!k]; f[ch[y][k]]=y;ch[x][!k]=y; f[y]=x; f[x]=z;pushup(y); pushup(x);
}
void splay(int x) {update(x);for(int fa;fa=f[x],!isrt(x);rotate(x))if(!isrt(fa))rotate(get(x)==get(fa)?fa:x);
}
void access(int p) {int t=0;while(p) {splay(p);rs=t;pushup(p);t=p;p=f[p];}
}
void makeroot(int p) {access(p); splay(p);swap(ls,rs); rev[p]^=1;
}
void link(int x,int p) {makeroot(x); splay(p); f[x]=p;
}
void cut(int x,int p) {makeroot(x); access(p); splay(p); ls=f[x]=0;
}
int find(int p) {access(p); splay(p);while(ls) pushdown(p),p=ls;return p;
}
int query(int x,int p) {makeroot(x); access(p); splay(p); return mx[p];
}
int now=1;
int calc() {while(kill[now]&&now<=m) now++;return a[now].v;
}
int main() {int ans=1<<30;scanf("%d%d",&n,&m);int i;for(i=1;i<=n;i++) mx[i]=i;for(i=1;i<=m;i++) {scanf("%d%d%d",&a[i].x,&a[i].y,&a[i].v);}sort(a+1,a+m+1,cmp);tot=n;int ne=0;for(i=1;i<=m;i++) {int x=a[i].x,y=a[i].y;tot++;if(x==y) {kill[i]=1;continue;}int dx=find(x),dy=find(y);if(dx!=dy) {ne++;val[tot]=a[i].v; mx[tot]=tot; link(x,tot); link(tot,y);}else {int k=query(x,y);kill[k-n]=1;// printf("%d %d %d\n",k,a[k-n].x,a[k-n].y);cut(a[k-n].x,k); cut(k,a[k-n].y);val[tot]=a[i].v; mx[tot]=tot; link(x,tot); link(tot,y);}if(ne==n-1) {ans=min(ans,calc()-a[i].v);}}printf("%d\n",ans);
}