#include <bits/stdc++.h>

using namespace std;

ifstream fin("flux.in");
ofstream fout("flux.out");

const double EPS = 1e-12;

struct Edge {
    int x, y;
    double c;
};

int n, m;
vector<Edge> edges;
double a[105][105], b[105], val[105];

int main() {
    fin >> n >> m;

    for (int i = 1; i <= m; ++i) {
        int x, y;
        double c;
        fin >> x >> y >> c;

        edges.push_back({x, y, c});

        if (x != 1 && x != n)
            ++a[x][x];

        if (y != 1 && y != n)
            ++a[y][y];

        if (x != 1 && x != n) {
            if (y != 1 && y != n)
                --a[x][y];
            else if (y == 1)
                b[x] += 1;
        }

        if (y != 1 && y != n) {
            if (x != 1 && x != n)
                --a[y][x];
            else if (x == 1)
                b[y] += 1;
        }
    }

    int sz = n - 2;

    for (int i = 2; i <= n - 1; ++i) {
        int pos = i;

        for (int j = i; j <= n - 1; ++j) {
            if (abs(a[j][i]) > abs(a[pos][i]))
                pos = j;
        }

        for (int j = i; j <= n - 1; ++j)
            swap(a[i][j], a[pos][j]);

        swap(b[i], b[pos]);

        for (int j = i + 1; j <= n - 1; ++j) {
            double coef = a[j][i] / a[i][i];

            for (int k = i; k <= n - 1; ++k)
                a[j][k] -= coef * a[i][k];

            b[j] -= coef * b[i];
        }
    }

    val[1] = 1;
    val[n] = 0;

    for (int i = n - 1; i >= 2; --i) {
        val[i] = b[i];

        for (int j = i + 1; j <= n - 1; ++j)
            val[i] -= a[i][j] * val[j];

        val[i] /= a[i][i];
    }

    double total = 0;
    double scale = 1e100;

    for (auto edge : edges) {
        double flow = abs(val[edge.x] - val[edge.y]);

        if (edge.x == 1)
            total += val[edge.x] - val[edge.y];

        if (edge.y == 1)
            total += val[edge.y] - val[edge.x];

        if (flow > EPS)
            scale = min(scale, edge.c / flow);
    }

    fout << fixed << setprecision(3) << total * scale << "\n";

    return 0;
}