using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        ++n;
        var map = NArr(m);
        var tree = new List<(int to, long len, long count)>[n];
        for (var i = 0; i < tree.Length; ++i) tree[i] = new List<(int to, long len, long count)>();
        var revtree = new List<int>[n];
        for (var i = 0; i < revtree.Length; ++i) revtree[i] = new List<int>();
        var refs = new int[n];
        foreach (var edge in map)
        {
            tree[edge[0]].Add((edge[1], edge[2], edge[3]));
            revtree[edge[1]].Add(edge[0]);
            ++refs[edge[1]];
        }
        var visited = new bool[n];
        var lengths = new long[n];
        var counts = new long[n];
        counts[0] = 1;
        var mod = 1_000_000_007;
        var q = new Queue<int>();
        for (var i = 0; i < n; ++i) if (refs[i] == 0)
        {
            visited[i] = true;
            q.Enqueue(i);
        }
        while (q.Count > 0)
        {
            var cur = q.Dequeue();
            foreach (var next in tree[cur])
            {
                counts[next.to] = (counts[next.to] + counts[cur] * next.count % mod) % mod;
                lengths[next.to] = (lengths[next.to] + counts[cur] * next.len % mod * next.count % mod +
                    lengths[cur] * Exp(counts[cur], mod - 2, mod) % mod * next.count % mod) % mod;
                --refs[next.to];
                if (refs[next.to] == 0)
                {
                    visited[next.to] = true;
                    q.Enqueue(next.to);
                }
            }
        }
        var reachable0 = new bool[n];
        DFS(0, tree, reachable0);
        var reachableN = new bool[n];
        DFS(n - 1, revtree, reachableN);
        for (var i = 0; i < n; ++i) if (reachable0[i] && reachableN[i] && !visited[i])
        {
            WriteLine("INF");
            return;
        }
        WriteLine(lengths[^1]);
    }
    static void DFS(int cur, List<(int to, long len, long count)>[] tree, bool[] visited)
    {
        visited[cur] = true;
        foreach (var next in tree[cur])
        {
            if (visited[next.to]) continue;
            DFS(next.to, tree, visited);
        }
    }
    static void DFS(int cur, List<int>[] tree, bool[] visited)
    {
        visited[cur] = true;
        foreach (var next in tree[cur])
        {
            if (visited[next]) continue;
            DFS(next, tree, visited);
        }
    }
    static long Exp(long n, long p, int mod)
    {
        long _n = n % mod;
        var _p = p;
        var result = 1L;
        if ((_p & 1) == 1) result *= _n;
        while (_p > 0)
        {
            _n = _n * _n % mod;
            _p >>= 1;
            if ((_p & 1) == 1) result = result * _n % mod;
        }
        return result;
    }
}