#include <bits/stdc++.h>   #pragma GCC optimize( Ofast )   using namespace std;   struct Edge {     long long int from, to, cap, flow, index;     Edge(long long int from, long long int to, long long int cap,          long long int flow, long long int index)         : from(from), to(to), cap(cap), flow(flow), index(index) {}   };   struct PushRelabel {     long long int N;     vector<vector<Edge>> G;     vector<long long> excess;     vector<long long int> dist, active, count;     queue<long long int> Q;     PushRelabel(long long int N)         : N(N), G(N), excess(N), dist(N), active(N), count(2 * N) {}     void AddEdge(long long int from, long long int to, long long int cap) {       G[from].push_back(Edge(from, to, cap, 0, G[to].size()));       if (from == to) G[from].back().index++;       G[to].push_back(Edge(to, from, 0, 0, G[from].size() - 1));     }     void Enqueue(long long int v) {       if (!active[v] && excess[v] > 0) {         active[v] = true;         Q.push(v);       }     }     void Push(Edge &e) {       long long int amt = min(excess[e.from], e.cap - e.flow);       if (dist[e.from] <= dist[e.to] || amt == 0) return;       e.flow += amt;       G[e.to][e.index].flow -= amt;       excess[e.to] += amt;       excess[e.from] -= amt;       Enqueue(e.to);     }     void Gap(long long int k) {       for (long long int v = 0; v < N; v++) {         if (dist[v] < k) continue;         count[dist[v]]--;         dist[v] = max(dist[v], N + 1);         count[dist[v]]++;         Enqueue(v);       }     }     void Relabel(long long int v) {       count[dist[v]]--;       dist[v] = 2 * N;       for (long long int i = 0; i < G[v].size(); i++)         if (G[v][i].cap - G[v][i].flow > 0)           dist[v] = min(dist[v], dist[G[v][i].to] + 1);       count[dist[v]]++;       Enqueue(v);     }     void Discharge(long long int v) {       for (long long int i = 0; excess[v] > 0 && i < G[v].size(); i++)         Push(G[v][i]);       if (excess[v] > 0) {         if (count[dist[v]] == 1)           Gap(dist[v]);         else           Relabel(v);       }     }     long long GetMaxFlow(long long int s, long long int t) {       count[0] = N - 1;       count[N] = 1;       dist[s] = N;       active[s] = active[t] = true;       for (long long int i = 0; i < G[s].size(); i++) {         excess[s] += G[s][i].cap;         Push(G[s][i]);       }       while (!Q.empty()) {         long long int v = Q.front();         Q.pop();         active[v] = false;         Discharge(v);       }       long long totflow = 0;       for (long long int i = 0; i < G[s].size(); i++) totflow += G[s][i].flow;       return totflow;     }   };   void solve() {     long long int n;     cin >> n;     long long int m;     cin >> m;     long long int x;     cin >> x;     vector<array<long long int, 3>> edge(m);     for (long long int i = 0; i < m; i++) {       cin >> edge[i][0];       edge[i][0]--;       cin >> edge[i][1];       edge[i][1]--;       cin >> edge[i][2];     }     long double low = 0;     long double high = 1e9;     for (long long int i = 0; i < 100; i++) {       long double mid = (low + high) / (long double)2;       PushRelabel G(n);       for (auto e : edge) {         G.AddEdge(e[0], e[1], (long long int)(e[2] / mid));       }       if (G.GetMaxFlow(0, n - 1) >= x) {         low = mid;       } else {         high = mid;       }     }     long double avg = (low + high) / (long double)2;     cout << fixed << setprecision(9) << (long double)x * avg <<   n ;   }   int32_t main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     solve();     cerr <<  Time :            << 1000 * ((long double)clock()) / (long double)CLOCKS_PER_SEC <<  ms n ;     return 0;   }