import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;
import java.util.ArrayDeque;
import java.util.Queue;
class Edge{
    int from;
    int to;
    long cost;
    Edge(int from,int to,long cost){
        this.from = from;
        this.to = to;
        this.cost = cost;
    }
}

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int n = fs.nextInt();
        int m = fs.nextInt();
        long max = 0;
        List<Edge> graph = new ArrayList<>();
        boolean[] visited = new boolean[n];
        int from,to;
        long cost;
        for(int i=0;i<m;i++){
            from = fs.nextInt()-1;
            to = fs.nextInt()-1;
            cost = fs.nextLong();
            graph.add(new Edge(from, to, cost));
        }
        long inf = 100000000000000L;
        long[] dist = new long[n];
        Arrays.fill(dist,-inf);
        dist[0] = 0;
        boolean update = false;
        for(int i = 0; i < n; i++){
          update = false;
          for(Edge e : graph){
            if(dist[e.from] != -inf){
              if(dist[e.to] < dist[e.from] +e.cost){
                dist[e.to] = dist[e.from] +e.cost;
                update = true;
              }
            }
          }
          if(i == 0){
            max = dist[n-1];
          }
          else if(i < n-1){
            max = Math.max(max,dist[n-1]);
          }
        }
        if(update == true && max < dist[n-1]){
          System.out.println("inf");
        }
        else{
          System.out.println(max);
        }
  }
}
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;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        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(){
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDoutble(){return Double.parseDouble(next());}
}

Measured memory_bytes: 22448