#include <cstdio> #include <cstring> #include <iostream> #include <string> #include <cmath> #include <bitset> #include <vector> #include <map> #include <set> #include <queue> #include <deque> #include <algorithm> #include <complex> #include <unordered_map> #include <unordered_set> #include <random> #include <cassert> #include <fstream> #define popcount __builtin_popcount using namespace std; typedef long long int ll; typedef pair<int, ll> P; int main() { int n, m; ll a; cin>>n>>m>>a; ll dp[100010]; fill(dp, dp+n+1, -a); dp[0]=0; vector<P> v[100010]; for(int i=0; i<m; i++){ int l, r; ll p; cin>>l>>r>>p; v[r].push_back({l, p}); } ll ans=0; ll mx[100010]; mx[0]=0; for(int i=1; i<=n; i++){ for(auto p:v[i]){ dp[i]=max({dp[i], dp[p.first-1]-a+p.second, mx[max(p.first-2, 0)]-2*a+p.second}); } mx[i]=max(mx[i-1], dp[i]); ans=max(dp[i], ans); } ans=max(ans, dp[n]+a); cout<<ans<<endl; return 0; }