#include <bits/stdc++.h>
#include <boost/multiprecision/cpp_int.hpp>
using namespace std;

//#define int long long
//using ll = boost::multiprecision::cpp_int;
using ll = long long;
//constexpr int INF = 1e9;//INT_MAX=(1<<31)-1=2147483647
constexpr ll INF = (ll)1e18;//(1LL<<63)-1=9223372036854775807
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr int dx[4]={1,0,-1,0};
constexpr int dy[4]={0,1,0,-1};
#ifdef LOCAL_ENV
	#define debug(var) std::cout<<#var" = "<<var<<std::endl
#else
	#define debug(var)
#endif
#define p(var) std::cout<<var<<std::endl
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define all(a) (a).begin(), (a).end()
#define PI (acos(-1))
template<typename T> inline T power(T x, T n){ return n ? power(x*x%MOD,n/2)*(n%2?x:1)%MOD : 1; }
template<typename T> inline T gcd(T a, T b) { return b ? gcd(b,a%b) : a; }
template<typename T> inline T lcm(T a, T b) { return a / gcd(a,  b) * b; }
template<typename T1, typename T2>inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template<typename T1, typename T2>inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& p) {return s << "(" << p.first << ", " << p.second << ")";}
template<typename T> ostream& operator<<(ostream& s, const vector<T>& v) {
	for (int i = 0, len = v.size(); i < len; ++i){
		s << v[i]; if (i < len - 1) s << "\t";
	}
	return s;
}
template<typename T> ostream& operator<<(ostream& s, const vector< vector<T> >& vv) {
	for (int i = 0, len = vv.size(); i < len; ++i){
		s << vv[i] << endl;
	}
	return s;
}
template<typename T1, typename T2> ostream& operator<<(ostream& s, const map<T1, T2>& m) {
	s << "{" << endl;
	for (typeof(m.begin()) itr = m.begin(); itr != m.end(); ++itr){
		s << "\t" << (*itr).first << " : " << (*itr).second << endl;
	}
	s << "}" << endl;
	return s;
}

/*-----8<-----8<-----*/

class Edge {
public:
	ll from,to,cost;
	Edge() {}
	Edge(ll from, ll to, ll cost) : from(from), to(to), cost(cost) {}
	bool operator < (const Edge &another) const {
		return cost != another.cost ? (cost > another.cost) : 
			(from != another.from ? from < another.from : to < another.to);
	}
};


bool bellman_ford(const vector<vector<Edge>> &g, ll start, vector<ll> &dist, vector<ll> &prev) {
	ll gsize = g.size();
	dist.assign(gsize, INF+INF); dist[start] = 0;
	prev.assign(gsize, -1);
	
	bool negative_cycle = false;
	for(ll k=0;k<gsize;k++){
		for(ll i=0;i<gsize;i++){
			for(auto e=(g[i]).begin(); e!=(g[i]).end(); e++){
				if (dist[e->to] > dist[e->from] + e->cost) {
					dist[e->to] = dist[e->from] + e->cost;
					prev[e->to] = e->from;
					if (k == gsize-1) {
						dist[e->to] = -INF;
						negative_cycle = true;
					}
				}
			}
		}
	}
	return negative_cycle;
}
//最短路木の親頂点を元にstart->goalの経路を作成
vector<ll> buildPath(const vector<ll> &prev, ll goal) {
	vector<ll> path;
	for (ll u = goal; u >= 0; u = prev[u])
		path.push_back(u);
	reverse(path.begin(), path.end());
	return path;
}



constexpr ll N_MAX = 1000;
constexpr ll C_I_MAX = 1000000000;

ll N, M;


void input() {
	ll N,M;
	cin >> N >> M;
	vector<vector<Edge>> g(N,vector<Edge>());
	for (ll i=0; i<M; i++) {
		ll from,to,cost;
		cin >> from >> to >> cost;
		from--;to--;
		Edge e=Edge(from,to,-cost);
		g[e.from].push_back(e);
	}
	vector<ll> dist, prev;
	bool negativecycle=bellman_ford(g, 0, dist, prev);
	debug(dist);
	if(negativecycle && dist[N-1]==-INF){p("inf");return;}
	p(-dist[N-1]);
}

signed main() {
	input();

	return 0;
}


Measured memory_bytes: 384