/**
 * Created at 12:41 on 2019-08-12
 */

import java.io.*;
import java.util.*;

public class Main {

  static FastScanner sc = new FastScanner();
  static PrintStream out = System.out;
  static PrintWriter pw = new PrintWriter(out);

  static final int[] dx = {0, 1, 0, -1};
  static final int[] dy = {-1, 0, 1, 0};

  static final long MOD = (long) (1e9 + 7);
  static final long INF = Long.MAX_VALUE / 2;

  public static class Solver {
    public Solver() {

      int N = sc.nextInt();
      int M = sc.nextInt();

      BellmanFord2 bell = new BellmanFord2(N, M);

      long cost = -bell.shortestPath(0, N-1);

      out.println(cost == INF ? "inf" : cost);

    }


    public class BellmanFord2 extends Graph {

      static final long INF = Long.MAX_VALUE / 2;

      int N, M;

      public BellmanFord2(int N, int M) {
        this.N = N;
        this.M = M;
        read(N, M, true);
      }

      /*
        sからgまでの最小コストを返す
        sからgの間に負の閉路がある場合は-INFを返す
        そもそもたどり着けない場合はINFを返す
       */
      public long shortestPath(int s, int g) {

        boolean[] reachableToG = reachableTo(g);

        for (int i = 0; i < N; i++) {
          nodes[i].cost = INF;
        }

        nodes[s].cost = 0;

        LinkedList<Node> queue = new LinkedList<Node>();

        queue.add(nodes[s]);

        while(!queue.isEmpty()) {

          Node from = queue.pollFirst();

          if (!reachableToG[from.id]) continue;

          for (Edge e: from.edgesTo) {

            Node to = e.to();

            long newCost = from.cost + e.cost;

            if (newCost < e.to().cost) {
              to.cost = newCost;
              to.prev = from.id;
              queue.add(to);
              to.depth = Math.max(to.depth, from.depth+1);

              if (to.depth >= N) return -INF;
            }

          }

        }

        return nodes[g].cost;
      }

      public boolean hasNegativeCycle(int s, int g) {

        for (int i = 0; i < N; i++) {
          nodes[i].cost = 0;
        }

        boolean updated;

        for (int t = 0; t < N; t++) {
          updated = false;

          for (int i = 0; i < N; i++) {
            Node from = nodes[i];
            for (Edge e : nodes[i].edgesTo) {
              Node to = e.to();
              long newCost = from.cost + e.cost;
              if (newCost < to.cost) {
                to.cost = newCost;
                updated = true;

                if (i == N-1) return true;
              }
            }
          }

          if (!updated) break;
        }

        return false;
      }

    }


    public class Graph {

      public int oneBased = 1;

      static final long INF = Long.MAX_VALUE / 2;

      Node[] nodes;

      int V,E;

      /*
       * N: 頂点の数
       * M: 辺の数
       * hasCost: 辺にコストがあるか
       */
      public void read(int N, int M, boolean hasCost) {
        V = N;
        E = M;

        nodes = new Node[N];
        for (int i=0; i<N; i++) {
          nodes[i] = new Node(i, INF);
        }

        for (int i=0; i<M; i++) {
          int from = sc.nextInt()-oneBased;
          int to = sc.nextInt()-oneBased;
          long cost = -(hasCost ? sc.nextLong() : 1);
          Edge e = new Edge(from, to, cost);
          nodes[from].edgesTo.add(e);
          nodes[to].edgesFrom.add(e);
        }
      }

      public class Node {
        int id;
        long cost;
        int prev;
        int depth;
        LinkedList<Edge> edgesFrom = new LinkedList(); //このノードを終点とする辺
        LinkedList<Edge> edgesTo = new LinkedList(); //このノードを始点とする辺
        boolean done = false;

        public Node(int id, long cost) {
          this.id = id;
          this.cost = cost;
          prev = -1;
          depth = 0;
        }

        //木構造だった場合
        public Node parent() {
          return nodes[edgesFrom.get(0).to];
        }
      }

      public class Edge {
        int from, to;
        long cost;
        public Edge(int from, int to, long cost) {
          this.from = from;
          this.to = to;
          this.cost = cost;
        }
        public Node from() {
          return nodes[from];
        }
        public Node getFrom() {return from(); }
        public Node to() {
          return nodes[to];
        }
        public Node getTo() { return to(); }
      }

      public boolean[] reachableFrom(int s) {
        boolean[] visited = new boolean[V];

        LinkedList<Node> stack = new LinkedList<Node>();

        stack.add(nodes[s]);

        while(!stack.isEmpty()) {
          Node from = stack.getLast();
          visited[from.id] = true;
          for (Edge e: from.edgesTo) {
            if (!visited[e.to]) {
              stack.add(e.to());
            }
          }
        }

        return visited;
      }

      public boolean[] reachableTo(int g) {
        boolean[] visited = new boolean[V];

        LinkedList<Node> stack = new LinkedList<Node>();

        stack.add(nodes[g]);

        while(!stack.isEmpty()) {
          Node to = stack.removeLast();
          visited[to.id] = true;
          for (Edge e: to.edgesFrom) {
            if (!visited[e.from]) {
              stack.add(e.from());
            }
          }
        }

        return visited;
      }
    }


  }

  public static void main(String[] args) {
    new Solver();
  }

  static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
      if (ptr < buflen) {
        return true;
      } else {
        ptr = 0;
        try {
          buflen = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (buflen <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) return buffer[ptr++];
      else return -1;
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    public boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) throw new NoSuchElementException();
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    public long nextLong() {
      if (!hasNext()) throw new NoSuchElementException();
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int N, boolean oneBased) {
      if (oneBased) {
        int[] array = new int[N + 1];
        for (int i = 1; i <= N; i++) {
          array[i] = sc.nextInt();
        }
        return array;
      } else {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
          array[i] = sc.nextInt();
        }
        return array;
      }
    }

    public long[] nextLongArray(int N, boolean oneBased) {
      if (oneBased) {
        long[] array = new long[N + 1];
        for (int i = 1; i <= N; i++) {
          array[i] = sc.nextLong();
        }
        return array;
      } else {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
          array[i] = sc.nextLong();
        }
        return array;
      }
    }
  }

}


Measured memory_bytes: 35284