#include <fstream>
#include <iomanip>
using namespace std;
ifstream f("tunel.in");
ofstream g("tunel.out");
int N,M;
double A[265][265];
double Grade[265];
const double EPS = 0.00000001;
double X[265];
void Read()
{
    f>>N>>M;
    for(int i=1;i<=M;i++)
    {
        int x,y,c;
        f>>x>>y>>c;
        Grade[x]++;
        Grade[y]++;
        A[x][N+1]-=c;
        A[y][N+1]-=c;
        A[x][y]++;
        A[y][x]++;
    }
    for(int i=1;i<N;i++)
        A[i][i]=-Grade[i],A[i][N]=0;
    for(int i=1;i<=N+1;i++)
        A[N][i]=0;
    A[N][N]=1;
}

void Gauss()
{
    int i=1,j=1;
    int M=N;
    while(i<=N&&j<=M)
        {
            int k;
            for(k=i;(A[k][j]<EPS&&A[k][j]>-EPS)&&k<=N;k++);
            if(k==N+1)
            {
                j++;
                continue;
            }
            if(k!=i)
                swap(A[i],A[k]);

            for(int l=j+1;l<=M+1;l++)
                A[i][l]/=A[i][j];
            A[i][j]=1;
            for(k=i+1;k<=N;k++)
                {
                    for(int l=j+1;l<=M+1;l++)
                        A[k][l]-=A[i][l]*A[k][j];
                    A[k][j]=0;
                }
        ++i;++j;
        }
    double S=0;
    for(i=N;i>=1;i--)
        {
            S=0;
            for(j=1;j<=M+1;j++)
                if(A[i][j]>EPS || A[i][j]<-EPS)
                    break;
            for(int k=j+1;k<=M;k++)
                S+=A[i][k]*X[k];
            X[i]=(A[i][M+1]-S)/A[i][i];
        }
    g<<fixed<<setprecision(10)<<X[1]<<"\n";
}
int main()
{
    Read();
    Gauss();
    return 0;
}