#include <bits/stdc++.h>
#define int long long

using namespace std;

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

struct drumuri{
    int node,cost;
};

int n,m,x,y,z,sol,inque[1020],ciclu[1020],drum[1020];
vector <drumuri> edges[1020];
queue <int> q;

bool bellman(int delta)
{
    while(!q.empty())
        q.pop();
    for(int i=1; i<=n; i++)
        drum[i]=0, ciclu[i]=inque[i]=1, q.push(i);
    while(!q.empty())
    {
        int x=q.front();
        q.pop(), inque[x]=0;
        for(auto y:edges[x])
            if(drum[x]+y.cost-delta<drum[y.node])
            {
                ciclu[y.node]++;
                if(ciclu[y.node]>n)
                    return 1;
                drum[y.node]=drum[x]+y.cost-delta;
                if(inque[y.node]==0)
                    q.push(y.node);
            }
    }
    return 0;
}

int32_t main()
{
    f>>n>>m;
    for(int i=1; i<=m; i++)
        f>>x>>y>>z, edges[x].push_back({y,z*100});
    int st=1, dr=INT_MAX-100;
    while(st<=dr)
    {
        int mij=(st+dr)/2;
        if(bellman(mij))
            sol=mij, dr=mij-1;
        else
            st=mij+1;
    }
    int x=sol/100, y=sol%100;
    g<<x<<'.';
    if(y<=9)
        g<<'0'<<y;
    else
        g<<y;
    return 0;
}