#include <iostream> #include <vector> #include <set> using namespace std; typedef long long ll; vector<pair<ll,ll>> v[100010]; set<ll> s; ll dp[100010],b[100010]; int main(){ ll i,j,n,m,a; cin >> n >> m >> a; for(i=0;i<m;i++){ ll l,r,p; cin >> l >> r >> p; l--; v[r].push_back({l,p}); if(r==n){ s.insert(l); b[l] = p; } } for(i=1;i<=n;i++){ dp[i] = -a; } dp[0] = 0; ll mx = 0; for(i=1;i<n;i++){ dp[i] = mx - a; for(j=0;j<v[i].size();j++){ dp[i] = max(dp[i],dp[v[i][j].first] + v[i][j].second - a); } mx = max(mx,dp[i]); } ll ans = -100000000000000; for(i=0;i<n;i++){ if(s.count(i)){ dp[i] += b[i]; } ans = max(ans,dp[i]); } cout << ans << endl; }