#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
#define pii pair<int,int>
#define ll long long
#define pb push_back
#define vi vector<int>
#define se second
#define fi first
using namespace std;
const int N = 1e5+5;
vector<pii> adj[N];
int n,m;
int A[N],B[N],W[N],NUM[N][2],MX[N];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 0; i < m; i++) {
int a,b,w;
cin >> a >> b >> w;
A[i] = a, B[i] = b;
W[i] = w;
NUM[i][0] = adj[a].size();
NUM[i][1] = adj[b].size();
adj[a].pb({b,w});
adj[b].pb({a,w});
MX[i] = w;
}
for (int i = m-2; i >= 0; i--)
MX[i] = max(MX[i],MX[i+1]);
ll ans = 0;
for (int i = 0; i < m; i++) {
int a = A[i], b = B[i];
adj[a][NUM[i][0]].se += MX[i+1];
adj[b][NUM[i][1]].se += MX[i+1];
// dijkstra
priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;
pq.push({0,1});
vector<bool> vis(n+1);
vector<ll> d(n+1);
d[0] = 0;
for (int i = 1; i <= n; i++)
d[i] = 10000000000000000;
while(!pq.empty()) {
auto i1 = pq.top();
pq.pop();
int v = i1.se;
if (vis[v]) continue;
ll dis = i1.fi;
if (v == n) {
ans = max(ans,dis);
break;
}
vis[v] = 1;
for (auto i : adj[v])
if (!vis[i.fi] && d[i.fi] > dis + i.se) {
d[i.fi] = dis + i.se;
pq.push({d[i.fi],i.fi});
}
}
// replace
adj[a][NUM[i][0]].se -= MX[i+1];
adj[b][NUM[i][1]].se -= MX[i+1];
}
cout << ans;
}
