#include <bits/stdc++.h>
using namespace std;
const int MOD = 1000 * 1000 * 1000 + 7;
void solve();
int main() {
  auto start = clock();
  cout.sync_with_stdio(0);
  cin.tie(0);
  cout.precision(10);
  cout << fixed;
  int t = 1;
  while (t--) {
    solve();
  }
  cerr << "\nTime: " << (clock() - start) / 1.0 / CLOCKS_PER_SEC << "\n";
  return 0;
}
const int MAXN = 59;
const int INF = 1000 * 1000;
struct edge {
  int a, b, cap, flow;
};
int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
vector<edge> e;
vector<int> g[MAXN];
void add_edge(int a, int b, int cap) {
  edge e1 = {a, b, cap, 0};
  edge e2 = {b, a, 0, 0};
  g[a].push_back((int)e.size());
  e.push_back(e1);
  g[b].push_back((int)e.size());
  e.push_back(e2);
}
bool bfs() {
  int qh = 0, qt = 0;
  q[qt++] = s;
  memset(d, -1, n * sizeof d[0]);
  d[s] = 0;
  while (qh < qt && d[t] == -1) {
    int v = q[qh++];
    for (size_t i = 0; i < g[v].size(); ++i) {
      int id = g[v][i], to = e[id].b;
      if (d[to] == -1 && e[id].flow < e[id].cap) {
        q[qt++] = to;
        d[to] = d[v] + 1;
      }
    }
  }
  return d[t] != -1;
}
int dfs(int v, int flow) {
  if (!flow) return 0;
  if (v == t) return flow;
  for (; ptr[v] < (int)g[v].size(); ++ptr[v]) {
    int id = g[v][ptr[v]], to = e[id].b;
    if (d[to] != d[v] + 1) continue;
    int pushed = dfs(to, min(flow, e[id].cap - e[id].flow));
    if (pushed) {
      e[id].flow += pushed;
      e[id ^ 1].flow -= pushed;
      return pushed;
    }
  }
  return 0;
}
int dinic() {
  int flow = 0;
  for (;;) {
    if (!bfs()) break;
    memset(ptr, 0, n * sizeof ptr[0]);
    while (int pushed = dfs(s, INF)) flow += pushed;
  }
  return flow;
}
struct Edge {
  int a, b, c;
};
int m, x;
vector<Edge> edges(m);
void buildGraph(double v) {
  e.clear();
  for (int i = 0; i < n; ++i) {
    g[i].clear();
  }
  for (int i = 0; i < m; ++i) {
    auto& e = edges[i];
    double c = edges[i].c / v;
    if (c > INF) {
      c = INF;
    }
    add_edge(e.a, e.b, floor(c));
  }
  s = 0;
  t = n - 1;
}
bool canSend(double v) {
  buildGraph(v);
  int f = dinic();
  return f >= x;
}
void solve() {
  cin >> n >> m >> x;
  edges.resize(m);
  for (int i = 0; i < m; ++i) {
    Edge& e = edges[i];
    cin >> e.a >> e.b >> e.c;
    --e.a;
    --e.b;
  }
  double L = 0;
  double R = 1000 * 1000.0;
  for (int it = 0; it < 100; ++it) {
    double M = (L + R) / 2;
    if (canSend(M)) {
      L = M;
    } else {
      R = M;
    }
  }
  cout << L * x << endl;
}
