#include <bits/stdc++.h>
using namespace std;
/*{{{*/  //template
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
constexpr int INF = numeric_limits<int>::max()/2;
constexpr long long LINF = numeric_limits<long long>::max()/3;
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define sz(x) (int)(x).size()
#define debug(x) cerr<<#x<<":"<<x<<endl
#define debug2(x,y) cerr<<#x<<","<<#y":"<<x<<","<<y<<endl
//struct fin{ fin(){ cin.tie(0); ios::sync_with_stdio(false); } } fin_;
struct Double{ double d; explicit Double(double x) : d(x){} };
ostream& operator<<(ostream& os,const Double x){ os << fixed << setprecision(20) << x.d; return os; }
template<typename T> ostream& operator<<(ostream& os,const vector<T>& vec){ os << "["; for(const auto& v : vec){ os << v << ","; } os << "]"; return os; }
template<typename T,typename U> ostream& operator<<(ostream& os, const map<T,U>& mp){ os << "{"; for(auto& p : mp){ os << p << ","; } os << "}"; return os; }
template<typename T,typename U> ostream& operator<<(ostream& os,const pair<T,U>& p){ os << "(" << p.first << ","<< p.second <<")"; return os; }
template<typename T> ostream& operator<<(ostream& os,const set<T>& st){ os<<"{"; for(T v:st) os<<v<<","; os <<"}"; return os; }
template<typename T,typename U> inline void chmax(T &x,U y){ if(y>x) x = y; }
template<typename T,typename U> inline void chmin(T &x,U y){ if(y<x) x = y; }
using ll = long long;
using ull = unsigned long long;
using pii = std::pair<int,int>;
using vi = std::vector<int>;
typedef vector<vi> vvi;
ll gcd(ll a,ll b){ if(b==0) return a; else return gcd(b,a%b); }
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }
//constexpr double eps = 1e-14; 
constexpr double eps = 1e-10; 
constexpr ll mod = 1e9+7;
const int dx[]={1,0,-1,0} ,dy[] = {0,1,0,-1};
/*}}}*/


struct BellmanFord{
    struct Edge{
        int from,to;
        long long cost;
        Edge(){}
        Edge(int from,int to,long long cost) : from(from),to(to),cost(cost) {}
    };

    int V;
    vector<Edge> es;
    vector<vector<int>> G,rG;
    vector<bool> reachable_from_s,reachable_from_t;
    BellmanFord(int v) : V(v), G(V), rG(V) {}

    void add_edge(int from,int to, long long cost){
        es.emplace_back(from,to,cost);
        G[from].push_back(to);
        rG[to].push_back(from);
    }

    /* グラフ上に負閉路があるかを判定 O(VE) */
    bool find_negative_loop(){
        vector<long long> d(V,0);
        for(int i=0;i<V;i++){
            for(const Edge& e : es){
                if(d[e.to] > d[e.from] + e.cost){
                    d[e.to] = d[e.from] + e.cost;
                    if(i==V) return true;
                }
            }
        }
        return false;
    }

    void dfs(int u){
        if(reachable_from_s[u]) return;
        reachable_from_s[u] = true;
        for(int v : G[u]){
            dfs(v);
        }
    }
    void rdfs(int u){
        if(reachable_from_t[u]) return;
        reachable_from_t[u] = true;
        for(int v : rG[u]){
            rdfs(v);
        }
    }

    /* 頂点sから頂点tへのパス上に負閉路があるかを判定 O(VE) */
    bool find_negative_path(int s,int t){
        reachable_from_s.resize(V); for(int i=0;i<V;i++) reachable_from_s[i] = false;
        reachable_from_t.resize(V); for(int i=0;i<V;i++) reachable_from_t[i] = false;
        dfs(s);
        rdfs(t);
        vector<bool> ok(V);
        for(int i=0;i<V;i++) ok[i] = reachable_from_s[i] && reachable_from_t[i];
        constexpr long long inf = 1LL << 60;
        vector<long long> d(V,inf);
        d[s] = 0;
        for(int i=0;i<2*V;i++){
            bool upd = false;
            for(auto& e : es){
                if(!ok[e.to]) continue;
                if(!ok[e.from]) continue;
                if(d[e.from] != inf && d[e.to] > d[e.from] + e.cost){
                    d[e.to] = d[e.from] + e.cost;
                    upd = true;
                }
            }
            if(upd && i >= V) return true;
        }
        return false;
    }

    /* 頂点sからの最短距離計算 */
    vector<long long> run(int s){
        constexpr long long inf = 1LL << 60;
        vector<long long> d(V,inf);
        d[s] = 0;
        for(int i=0;i<V;i++){
            for(const Edge& e : es){
                if(d[e.from] != inf && d[e.to] > d[e.from] + e.cost){
                    d[e.to] = d[e.from] + e.cost;
                }
            }
        }
        return d;
    }
};

int main(){
    ll n,m,p; cin >> n >> m >> p;
    BellmanFord graph(n);
    rep(i,m){
        int u,v; ll c;
        cin >> u >>  v >> c;
        u--; v--;
        c -= p;
        graph.add_edge(u,v,-c);
    }


    if(graph.find_negative_path(0,n-1)){
        cout << -1 << endl;
        return 0;
    }else{
        auto d = graph.run(0);
        cout << max(0LL, -d[n-1]) << endl;
    }
}


Measured memory_bytes: 640