#include <fstream>
#include <climits>
#include <vector>
#include <queue>
#include <string.h>

#define NMAX 1005

using namespace std;

ifstream f("ciclu.in");
ofstream g("ciclu.out");

int n, m, x, y, cost, left1, right1, answerProblem;
int timesInQueue[NMAX];
long long int answer[NMAX];
vector < pair <int, int> > v[NMAX];
queue <int> que;

bool isCycle(int scad) {
    memset(timesInQueue, 0, sizeof(timesInQueue));

    while (!que.empty())
        que.pop();

    for (int i = 1; i <= n; i++) {
        answer[i] = INT_MAX / 2;
    }

    que.push(0);

    while (!que.empty()) {
        int node = que.front();
        que.pop();

        for (auto neighbour : v[node]) {

            if (answer[neighbour.first] > answer[node] + neighbour.second - scad) {
                answer[neighbour.first] = answer[node] + neighbour.second - scad;

                que.push(neighbour.first);
                timesInQueue[neighbour.first]++;

                if (timesInQueue[neighbour.first] == n)
                    return 1;
            }
        }
    }

    return 0;
}

int main()
{
    f >> n >> m;
    for (int i = 1; i <= m; i++) {
        f >> x >> y >> cost;

        v[x].push_back({y, cost * 100});
        right1 = max(right1, cost * 100);
    }

    for (int i = 1; i <= n; i++)
        v[0].push_back({i, 0});

    while (left1 <= right1) {
        int mid = (left1 + right1) / 2;

        if (isCycle(mid)) {
            right1 = mid - 1;
            answerProblem = mid;
        } else {
            left1 = mid + 1;
        }
    }

    answerProblem--;
    g << answerProblem / 100 << "." << answerProblem % 100 << "\n";
    return 0;
}