#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#include <random>
//#include "util.k"

using namespace std;

//呪文
#define DUMPOUT cout
#define dump(...) DUMPOUT<<"  ";DUMPOUT<<#__VA_ARGS__<<" :["<<__LINE__<<":"<<__FUNCTION__<<"]"<<endl;DUMPOUT<<"    ";dump_func(__VA_ARGS__)

typedef unsigned uint; typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> pii; typedef pair<ll, ll> pll; typedef pair<double, double> pdd; typedef pair<string, string> pss;
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const pair<_KTy, _Ty>& m) { ostr << "{" << m.first << ", " << m.second << "}"; return ostr; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const map<_KTy, _Ty>& m) { if (m.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { ostr << ", " << *itr; } ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const vector<_Ty>& v) { if (v.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const set<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const stack<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } stack<_Ty> t(s); ostr << "{" << t.top(); t.pop(); while (!t.empty()) { ostr << ", " << t.top(); t.pop(); } ostr << "}";	return ostr; }
template <typename _KTy, typename _Ty> istream& operator >> (istream& istr, pair<_KTy, _Ty>& m) { istr >> m.first >> m.second; return istr; }
template <typename _Ty> istream& operator >> (istream& istr, vector<_Ty>& v) { for (size_t i = 0; i < v.size(); i++) istr >> v[i]; return istr; }
ll modpow(ll n, ll p, ll m) { ll result = 1; while (p > 0) { if (p & 1) result = (result * n) % m; p >>= 1; n = (n * n) % m; } return result; }
template <typename _Ty> _Ty ipow(_Ty x, _Ty n) { _Ty ret = _Ty(1); for (_Ty i = _Ty(0); i < n; i++) ret *= x; return ret; }
template<typename A, size_t N, typename T> inline void Fill(A(&array)[N], const T &val) { std::fill((T*)array, (T*)(array + N), val); }

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail> void dump_func(Head&& head, Tail&&... tail) { DUMPOUT << head; if (sizeof...(Tail) == 0) { DUMPOUT << " "; } else { DUMPOUT << ", "; } dump_func(std::move(tail)...); }

#define PI 3.14159265358979323846
#define EPS 1e-11
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define all(x) (x).begin(), (x).end()
#define fake false



class edge {
public:
	ll from, to, cost;

	edge() : from(0), to(0), cost(0) {}
	edge(ll from, ll to) : from(from), to(to), cost(1) {}
	edge(ll from, ll to, ll cost) : from(from), to(to), cost(cost) {}
};

// Bellman-Ford 法
// es : 辺の集合, V : 頂点の数, s : スタート地点
class BellmanFord {

	const ll INF;

	// d[j] : 始点 s から頂点 j への最短距離
	// d[j] = min(d[j] + (j から j への辺のコスト) | e = (j, j) in E)
	vector<ll> d;
	vector<int> prev;
	bool negative_loop;

public:

	BellmanFord(const vector<edge>& es, int V, int s)
		: INF(1LL << 50), d(V, INF), prev(V, -1), negative_loop(false) {
		int E = es.size();

		d[s] = 0;
		for (int i = 0; i < V; i++) {
			bool update = false;
			for (int j = 0; j < E; j++) {
				edge e = es[j];
				// d[e.from] に(暫定)最短距離が既に記録されていて，
				// d[e.to] よりも d[e.from] から辺 e を通って
				// 頂点 e.to に行くほうがコストが低い場合は更新
				if (d[e.from] != INF && d[e.to] > d[e.from] + e.cost) {
					d[e.to] = d[e.from] + e.cost;
					prev[e.to] = e.from;
					update = true;

					if (i == V - 1 && e.to == V - 1) {
						negative_loop = true;
						return;
					}
				}
			}
			if (!update) break;
		}
	}

	vector<ll> shortest_path_cost() { return d; }
	ll shortest_path_cost(int v) { return d[v]; }

	vector<int> get_path(int t) {
		vector<int> path;
		if (negative_loop) {
			cout << "negative loop" << endl;
			return path;
		}
		// t が s になるまで prev[t] を辿っていく
		for (; t != -1; t = prev[t]) path.push_back(t);
		reverse(all(path));
		return path;
	}

	bool has_negative_loop() { return negative_loop; }

};

int main()
{
	//clock_t start, end;
	//start = clock();

	ios::sync_with_stdio(false);
	cin.tie(0);

	ll N, M;
	cin >> N >> M;

	vector<edge> es;

	REP(i, M) {
		ll a, b, c;
		cin >> a >> b >> c;
		a--; b--;

		es.push_back(edge(a, b, -c));
	}

	BellmanFord bf(es, N, 0);

	if (bf.has_negative_loop()) {
		cout << "inf" << endl;
	}
	else {
		cout << -bf.shortest_path_cost(N - 1) << endl;
	}

	//end = clock();
	//printf("%d msec.\n", end - start);

	return 0;
}

Measured memory_bytes: 384