//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

constexpr LL INF = 1e16;

struct edge {
    int from;
    int to;
    LL cost;
};

bool dijkstra(int N, int M, vector<LL> &dist, vector<edge> &edges) {
    dist[0] = 0;
    for (int i = 0; i < 2 * N; i++) {
        for (int j = 0; j < M; j++) {
            edge &e = edges[j];
            if (dist[e.from] != -INF) {
                dist[e.to] = max(dist[e.to], dist[e.from] + e.cost);
            }
        }
    }
    LL origin = dist[N - 1];
    for (int i = 0; i < 2 * N; i++) {
        for (int j = 0; j < M; j++) {
            edge &e = edges[j];
            if (dist[e.from] != -INF) {
                dist[e.to] = max(dist[e.to], dist[e.from] + e.cost);
            }
        }
    }
    return origin == dist[N - 1];
}

int main() {

    int N, M;
    cin >> N >> M;

    vector<edge> edges(M);
    for (int i = 0; i < M; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        a--, b--;
        edges[i] = edge({a, b, c});
    }

    vector<LL> dist(N, -INF);

    bool good = dijkstra(N, M, dist, edges);

    if (good) cout << dist[N - 1];
    else cout << "inf";

    return 0;
}










































Measured memory_bytes: 256