bool M1;
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<climits>
#include<iomanip>
#include<cassert>
#include<random>
#include<cstdio>
#include<vector>
#include<bitset>
#include<stack>
#include<queue>
#include<deque>
#include<cmath>
#include<ctime>
#include<map>
#include<set>
//#include<ext/pb_ds/assoc_container.hpp>
//#include<ext/pb_ds/hash_policy.hpp>
//#include<ext/pb_ds/priority_queue.hpp>
#define fi first
#define se second
#define LD double
#define name(x) #x
#define ll long long
#define Vector Point
#define I128 __int128
#define ull unsigned ll
#define pii pair<int,int>
#define pb(x) push_back(x)
#define dek(x) debug(x)<<" "
#define deh(x) debug(x)<<endl
#define syt cerr<<"sytakioi\n"
#define debug(x) cout<<name(x)<<":"<<x
#define F(i,a,b) for(int i=a,i##end=b;i<=i##end;++i)
#define UF(i,a,b) for(int i=a,i##end=b;i>=i##end;--i)
#define look_memory cerr<<abs(&M2-&M1)/1024.0/1024<<'\n'
#define rd_i(l,r) uniform_int_distribution<int>(l,r)(rd)
#define rd_r(l,r) uniform_real_distribution<double>(l,r)(rd)
#define look_time cerr<<(clock()-Time)*1.0/CLOCKS_PER_SEC<<'\n'
using namespace std;
//using namespace __gnu_cxx;
mt19937 rd(time(0));
const int N=3e5+5;
int n,m;
vector<pii> e[N];
int mn[N];
queue<int> q;
inline bool check(ll mx){
	memset(mn,-1,sizeof mn);
	mn[1]=0;q.emplace(1);
	while(!q.empty()){
		int u=q.front();q.pop();
		for(pii x:e[u]) if((!~mn[x.fi])&&(mn[u]+1ll)*x.se<=mx) mn[x.fi]=mn[u]+1,q.emplace(x.fi);
	}
	return ~mn[n];
}
bool M2;
int main(){
	int Time=clock();
	look_memory;
	cin.tie(nullptr)->sync_with_stdio(false);
	cin>>n>>m;
	F(i,1,m){
		int u,v,w;cin>>u>>v>>w;
		e[u].emplace_back(v,w);
	}
	ll l=1,r=1e15,ans=1e15;
	while(l<=r){
		ll mid=(l+r)>>1;
		if(check(mid)) r=mid-1,ans=mid;
		else l=mid+1;
	}
	cout<<ans<<'\n';
	look_time;
	return 0;
}