#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define pb push_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001;
const int INF=1001001001;
const int mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){if((ll)(a)==inf)cout<<"inf"<<'\n';else if((ll)(a)==-inf)cout<<"-inf"<<'\n';else cout<<a<<'\n';}
template<class T> void outs(T a){if((ll)(a)>=inf-100||(ll)(a)<=-inf+100)cout<<"-1"<<'\n';else cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';if((ll)(v[i])==inf)cout<<"inf";else if((ll)(v[i])==-inf)cout<<"-inf";else cout<<(ll)(v[i]);}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){a%=mod;if(b==0)return 1;if(b&1)return a*modpow(a,b-1)%mod;ll k=modpow(a,b/2);return k*k%mod;}
vb from1,ton;
void fromdfs(int i,vvp v){
   for(auto x: v[i]){
      if(from1[x.fi])continue;
      from1[x.fi]=true;
      fromdfs(x.fi,v);
   }
}
void todfs(int i,vvp v){
   for(auto x: v[i]){
      if(ton[x.fi])continue;
      ton[x.fi]=true;
      todfs(x.fi,v);
   }
}
int main(){
   ll n,m,p;cin>>n>>m>>p;
   from1=vb(n,false);
   ton=vb(n,false);
   vvp g(n);
   vvp rg(n);
   vvp e(n);
   vi dis(n,inf);
   dis[0]=0;
   rep(i,m){
      ll a,b,c;cin>>a>>b>>c;
      a--;b--;
      g[a].eb(b,-c+p);
      rg[b].eb(a,-c+p);
   }
   from1[0]=true;
   ton[n-1]=true;
   fromdfs(0,g);
   todfs(n-1,rg);
   if(!from1[n-1])dame(-1);
   rep(i,n){
      if(!from1[i]||!ton[i])continue;
      for(auto x:g[i]){
         if(from1[x.fi]&&ton[x.fi])e[i].pb(x);
      }
   }
   bool dif=true;
   int step=0;
   while(dif){
      dif=false;
      rep(i,n){
         if(dis[i]==inf)continue;
         for(auto x: e[i]){
            if(chmin(dis[x.fi],dis[i]+x.se))dif=true;
         }
      }
      step++;
      if(step>n)dame(-1);//負の閉路がある
   }
   out(max(-dis[n-1],0ll));
}

Measured memory_bytes: 342784