#include<fstream>
#include<iomanip>
#define eps 0.0000000001
using namespace std;
int n, m, x, y, i, j, ii, jj;
int d[105][105], viz[105];
double z, c[105][105], f[105][105], a[105][105], s[105], sol;
ifstream fin("flux.in");
ofstream fout("flux.out");
double modul(double x){
    if(x > 0){
        return x;
    }
    return -x;
}
void dfs(int nod){
    viz[nod] = 1;
    for(int i = 1; i <= n; i++){
        f[nod][i] = s[i] - s[nod];
        if(viz[i] == 0){
            dfs(i);
        }
    }
}
int main(){
    fin>> n >> m;
    for(i = 1; i <= n; i++){
        for(j = 1; j <= n; j++){
            c[i][j] = 1000000;
        }
    }
    for(i = 1; i <= m; i++){
        fin>> x >> y >> z;
        c[x][y] = c[y][x] = min(c[x][y], z);
        d[x][y]++;
        d[y][x]++;
    }
    for(i = 2; i <= n; i++){
        for(j = 1; j <= n; j++){
            if(i != j){
                a[i][j] = d[i][j];
                a[i][i] -= d[i][j];
            }
        }
    }
    a[n][n + 1] = 1;
    i = 2;
    j = 2;
    while(i <= n && j <= n){
        for(ii = i; ii <= n; ii++){
            if(modul(a[i][j]) >= eps){
                break;
            }
        }
        if(ii == n + 1){
            j++;
            continue;
        }
        if(ii != i){
            for(jj = j; jj <= n + 1; jj++){
                swap(a[i][jj], a[ii][jj]);
            }
        }
        for(jj = j + 1; jj <= n + 1; jj++){
            a[i][jj] /= a[i][j];
        }
        a[i][j] = 1;
        for(ii = i + 1; ii <= n; ii++){
            for(jj = j + 1; jj <= n + 1; jj++){
                a[ii][jj] -= a[i][jj] * a[ii][j];
            }
            a[ii][j] = 0;
        }
        i++;
        j++;
    }
    for(i = n; i >= 2; i--){
        for(j = 2; j <= n + 1; j++){
            if(modul(a[i][j]) >= eps){
                break;
            }
        }
        s[j] = a[i][n + 1];
        for(jj = n; jj > j; jj--){
            s[j] -= a[i][jj] * s[jj];
        }
    }
    dfs(1);
    if(viz[n] == 0){
        fout<<"0.000\n";
    }
    sol = 1000000000;
    for(i = 1; i <= n; i++){
        for(j = 1; j <= n; j++){
            if(d[i][j] != 0 && f[i][j] > 0){
                sol = min(sol, c[i][j] / f[i][j]);
            }
        }
    }
    fout<< setprecision(3) << fixed << sol <<"\n";
    return 0;
}