#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define REPR(i,n) for (int i=(int)(n)-1;i>=0;--i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define valid(y,x,h,w) (0<=y&&y<h&&0<=x&&x<w)
#define tpl(...) make_tuple(__VA_ARGS__)
const int INF = 0x3f3f3f3f;
const double EPS = 1e-8;
const double PI = acos(-1);
const int dy[] = {-1,0,1,0};
const int dx[] = {0,1,0,-1};
typedef long long ll;
typedef pair<int,int> pii;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename Ch,typename Tr,typename C,typename=decltype(begin(C()))>basic_ostream<Ch,Tr>& operator<<(basic_ostream<Ch,Tr>&os,
const C& c){os<<'[';for(auto i=begin(c);i!=end(c);++i)os<<(i==begin(c)?"":" ")<<*i;return os<<']';}
template<class S,class T>ostream&operator<<(ostream &o,const pair<S,T>&t){return o<<'('<<t.first<<','<<t.second<<')';}
template<int N,class Tp>void output(ostream&,const Tp&){}
template<int N,class Tp,class,class ...Ts>void output(ostream &o,const Tp&t){if(N)o<<',';o<<get<N>(t);output<N+1,Tp,Ts...>(o,t);}
template<class ...Ts>ostream&operator<<(ostream&o,const tuple<Ts...>&t){o<<'(';output<0,tuple<Ts...>,Ts...>(o,t);return o<<')';}
template<class T>void output(T t,char z=10){if(t<0)t=-t,putchar(45);int c[20];
int k=0;while(t)c[k++]=t%10,t/=10;for(k||(c[k++]=0);k;)putchar(c[--k]^48);putchar(z);}
template<class T>void outputs(T t){output(t);}
template<class S,class ...T>void outputs(S a,T...t){output(a,32);outputs(t...);}
template<class T>void output(T *a,int n){REP(i,n)cout<<a[i]<<(i!=n-1?',':'\n');}
template<class T>void output(T *a,int n,int m){REP(i,n)output(a[i],m);}
template<class T>bool input(T &t){int n=1,c;for(t=0;!isdigit(c=getchar())&&~c&&c-45;);
if(!~c)return 0;for(c-45&&(n=0,t=c^48);isdigit(c=getchar());)t=10*t+c-48;t=n?-t:t;return 1;}
template<class S,class ...T>bool input(S&a,T&...t){input(a);return input(t...);}
template<class T>bool inputs(T *a, int n) { REP(i,n) if(!input(a[i])) return 0; return 1;}

typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight < f.weight :
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void shortestPath(const Graph g, int s, vector<Weight> &dist, vector<int> &prev) {
  int n = g.size();
  dist.assign(n, INF);
  dist[s] = 0;
  prev.assign(n, -2);
  vector<bool> loop(n);
  REP(k, n) REP(i, n) FOR(e,g[i]) {
    if (dist[e->dst] > dist[e->src] + e->weight) {
      dist[e->dst] = dist[e->src] + e->weight;
      prev[e->dst] = e->src;
      if (k == n-1) {
        loop[e->dst] = 1;
      }
    }
  }
  REP(i,n) if (loop[i]) dist[i] = -INF;
}

vector<bool> get_reachable(const Graph &g, int s) {
  int n = g.size();
  vector<bool> reachable(n);
  queue<int> Q;
  Q.push(s);
  reachable[s] = 1;
  while (!Q.empty()) {
    auto v = Q.front(); Q.pop();
    FOR(it, g[v]) {
      int u = it->dst;
      if (!reachable[u]) {
        reachable[u] = 1;
        Q.push(u);
      }
    }
  }
  return reachable;
}

int main() {
  int n,m,p;
  while(input(n,m,p)) {
    Graph g(n);
    Graph revg(n);
    REP(i,m) {
      int a,b,c;
      input(a,b,c);
      a--;b--;
      g[a].emplace_back(a,b,p-c);
      revg[b].emplace_back(b,a,1);
    }
    vector<Weight> dist;
    vector<int> prev;
    shortestPath(g, 0, dist, prev);
    auto reachable = get_reachable(g, 0);
    auto reachable_rev = get_reachable(revg, n-1);
    bool inf = 0;
    // cout << reachable << endl << reachable_rev << endl << dist << endl;
    REP(i,n) {
      if (reachable[i] && reachable_rev[i] && dist[i] == -INF) {
        inf = 1;
      }
    }
    if (inf) cout << -1 << endl;
    else cout << max(0,-dist[n-1]) << endl;
  }
}


Measured memory_bytes: 768